1977 Mercury Comet Differentials

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Keep Your 1977 Mercury Comet in Top Shape with Quality Differentials

Whether you’re repairing or upgrading your Differential, using high-quality parts is key to keeping your 1977 Mercury Comet looking sharp and performing at its best. At Advance Auto Parts we carry a wide selection of dependable options, including Differential Pinion Seals, Front Differential Pinion Bearings, and Differential Bearings. Whether you’re replacing a damaged part or enhancing your truck’s style and protection, you’ll find exactly what you need to get the job done right.

Top-Rated Differentials from Trusted Brands

Looking for a reliable Differential? We’ve got you covered with options from brands you know and trust like National, Motive Gear, and Powertrax. For example, National Differentials start at just $12.99 with an average 4.3 star rating. Motive Gear and Powertrax offer similar pricing and quality, backed by strong customer feedback. With over 75 reviews and a solid 5 star average, you can shop with confidence knowing other Mercury Comet owners approve.

Explore Related Parts

While you’re upgrading or replacing your Differential, don’t forget to check out other key components like Drive Shafts and Axles and Universal Joints. At Advance Auto Parts, we’re here to help you keep your 1977 Mercury Comet in peak condition, inside and out.

Essential 1977 Mercury Comet Differentials

Yukon Gear – Grizzly Locker For Ford 8" With 31 Spline Axles (Part No.28007)

Grizzly Locker For Ford 8" With 31 Spline Axles

from

$941.99
The Yukon Grizzly Locker is the ultimate in locking differentials for street, off-road, & drag racing. Grizzly Lockers provide 100% power to both tires, while still allowing for disengagement while negotiating turns. The Yukon Grizzly locker is a mechanical locking differential. It features a forged case and 8620 internals for maximum strength. It’s patented design reduces common locker failures. All units assembled in the USA! All Grizzly Lockers are backed by the best warranty in the business! Yukon covers the replacement unit and covers any collaterally damaged parts and associated labor, up to $2,000!

Product Features:
  • Fits Ford 8″ with 31 spline axles
  • Patented internal design reduces common locker failures
  • 8620 internals for added strength
  • Assembled in the USA
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Yukon Gear – Heavy Duty Carrier Bearing Puller Set (Part No.56072)

Heavy Duty Carrier Bearing Puller Set

from

$883.99
Yukon Gear & Axle tools are made to the highest industry standard.

Product Features:
  • Works on popular Ford, GM, Chrysler, and many other housings
  • For differentials with XHD Clamshells
  • Can accommodate up to one-ton applications
  • Comes with a handy bench-top stand
  • This top-quality differential tool is built to last
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Yukon Gear – Grizzly Locker For Ford 9" With 31 Spline Axles (Part No.28009)

Grizzly Locker For Ford 9" With 31 Spline Axles

from

$929.99
The Yukon Grizzly Locker is the ultimate in locking differentials for street, off-road, & drag racing. Grizzly Lockers provide 100% power to both tires, while still allowing for disengagement while negotiating turns. The Yukon Grizzly locker uses 8620 internals and a patented design to provide maximum strength and reduce common failures. Assembled in the USA! This unit has been approved for competition in NASCAR National & Touring series. All Grizzly Lockers are backed by the best warranty in the business! Yukon covers the replacement unit and covers any collaterally damaged parts and associated labor, up to $2,000! This locker also fits 9.5″ & 10″ dropouts.

Product Features:
  • Fits Ford 9″ with 31 spline axles
  • Patented internal design reduces common locker failures
  • 8620 internals for added strength
  • Assembled in the USA
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Yukon Gear – 7.25" Ford & 6.75" Ford Pinion Seal (Part No.30173)

7.25" Ford & 6.75" Ford Pinion Seal

from

$55.99
Yukon Mighty Seals use the latest design and manufacturing technologies to produce a precision fit that seals tight and lasts for years to come.

Product Features:
  • Pinion seal
  • Fits Ford 6.75″ and 7.25″
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Richmond Gear – Differential Pinion Shaft (Part No.CSPF9)

Differential Pinion Shaft

from

$26.49
Richmond Gear is the leading manufacturer of professional quality, high-performance drivetrain products. Our complete line of products ranges from high performance ring-and-pinion sets for serious street and racing applications to torque-hungry manual transmissions and components. Richmond Gear products have been winners both at the Daytona 500 and U.S. Nationals for decades. WINNERS RUN RICHMOND.

Product Features:
  • For over 80-years, the Richmond Double-Diamond logo has represented some of the highest quality gears in the racing industry. Winners Run Richmond.
  • The superior quality of Richmond gearsets is a result of outstanding design, world class manufacturing and an extensive testing process that is performed on all products.
  • Richmond performance gearsets have been winners for decades at: NHRA, NMRA, NMCA, Daytona 500, WISSOTA and U.S. Nationals.
  • Richmond Gear is a leading manufacturer of high performance ring and pinion gearsets and drivetrain components, backed by limited warranty.
  • Engineered to perform faster and be more reliable, Richmond performance drivetrain products are the result of a continuous research and development program combined with state-of-the-art manufacturing capabilities.
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Yukon Gear – Adjuster lock bolt 3.062" & 3.250" Yukon Ford 9" Drop Out (Part No.32149)

Adjuster lock bolt 3.062" & 3.250" Yukon Ford 9" Drop Out

from

$3.99
Yukon Gear & Axle dropouts are heavy duty. They feature upgraded nodular iron construction and a larger-than-OEM design to provide unrivaled strength and reliability in racing and off-road applications.

Product Features:
  • Side adjuster lock bolt
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Powertrax – Differential Lock Assembly (Part No.9206902800)

Differential Lock Assembly

from

$551.99
For vehicles that are driven daily, the Power Trax No-Slip Traction System is the latest design in quiet traction-adding differential technology. It combines the automatic street-friendly smooth operation of a limited-slip differential with the traction performance of a locking differential. The Power Trax No-Slip locker easily installs in to your differential carrier using basic tools and without affecting your ring and pinion settings. Power Trax Grip-Lok, Lock-Right Lockers and No-Slip Traction Systems automatically provide 100% traction on-demand, under the toughest circumstances. The Power Trax Grip-Pro and Grip-LS performance limited slips offer smooth dependable torque transfer and traction for the best of both worlds.

Product Features:
  • The Power Trax Lock-Right Locker provides outstanding traction for off-road machines and race vehicles. Power Trax No-Slip Traction Systems deliver excellent performance to street-driven cars and trucks.
  • Power Trax lockers range from the original, Lock-Right for serious straight-line performance, to the No-Slip traction system for street-able vehicles.
  • Power Trax offers three levels of GRIP locking differentials, ranging from the clutch-type GRIP LS with a forged steel case, the gear-driven GRIP PRO and finally the GRIP LOK for extreme traction.
  • Power Trax ia an Extreme Traction System
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Motive Gear – Differential Gear Install Kit (Part No.F8IK)

Differential Gear Install Kit

from

$44.49
All Motive Gear products are engineered for their specific application and manufactured in state of the art facilities. All of our products undergo rigid quality control processes to insure proper fit, performance and longevity. Motive Gear products can be found in the winners circle at NHRA, IHRA, NMRA, NMCA, SODA, SCORE, BITD, Ultra-4 and NASCAR events because we offer unmatched selection and quality demanded by racers and their crew chiefs – the same quality and selection demanded by DIY customers and top mechanics. With four warehouses strategically located across North America, most Motive Gear orders arrive within 2-4 days. Win with Motive Gear!
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Yukon Gear – Pinion Nut (Part No.33154)

Pinion Nut

from

$7.99
Yukon Gear & Axle manufactures a full line of top quality small parts to complete any job including ring gear bolts, crush sleeves, pinion nuts and washers, axle studs, thrust washers and much, much more. For all your differential small parts needs, look no further than Yukon.

Product Features:
  • Pinion nut for Ford 7.5″, 8″ and 9″
  • 3/4″ x 20 thread
  • 1 1/6″ socket
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Yukon Gear – Pinion Install Kit for Ford 9" Differential (Part No.13042)

Pinion Install Kit for Ford 9" Differential

from

$175.99
Yukon Pinion Installation Kits are a terrific solution for gear installation on lower mileage vehicles where the carrier bearings and races can be reused. This kit features Timken bearings and races along with high-quality seals and small parts. Yukon does extensive research for each application to make sure your kit will arrive with all the correct parts you need to install your gear set.

Product Features:
  • Fits Ford 9″ without aftermarket Daytona pinion support
  • Included are pinion bearings and races, pinion seal, pilot bearing , crush sleeve , complete pinion shim kit, and marking compound with brush.
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Mr. Gasket – Rear End Gasket – Ford 9" – Blend Of Nitrile Rubber And Fiber For Excellent Sealing And Durability (Part No.82)

Rear End Gasket - Ford 9" - Blend Of Nitrile Rubber And Fiber For Excellent Sealing And Durability

from

$25.99
Mr. Gasket Axle Housing/Differential Cover or Rear End Gaskets are manufactured from a .047 inch thick cellulose/nitrile composite gasket material for excellent sealing and durability. They are precision die-cut for an excellent fit. Fits 1957-1981 Ford 10 bolt 9 inch ring gear.

Product Features:
  • .047″ thick cellulose/nitrile composite gasket material
  • Precision die cut
  • Reusable
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Yukon Gear – 9" 3.250" Aluminum Case, HD Drop Out Housing, With Load Bolt (Part No.32152)

9" 3.250" Aluminum Case, HD Drop Out Housing, With Load Bolt

from

$1070.00
9″ Yukon 3.250″ aluminum case, HD Drop Out housing, with load bolt. Made from A356-T6 aluminum & featuring a through bolt design, this dropout is rated for up to 1400 horsepower!

Product Features:
  • Fits Ford 9″
  • 3.250″ carrier race diameter
  • A356-T6 aluminum
  • Thru-bolt design added strength
  • With load bolt
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Pro-King – Differential Crush Sleeve (Part No.761A034)

Differential Crush Sleeve

from

$2.99
Pro-King is the leading supplier of transmission and driveline products in the aftermarket.

Product Features:
  • Meets or exceeds OE specifications
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Yukon Gear – Star Washers, 3.250" Ford 9" Drop Out New Design Only (Part No.32144)

Star Washers, 3.250" Ford 9" Drop Out New Design Only

from

$4.99
Yukon Gear & Axle dropouts are heavy duty. They feature upgraded nodular iron construction and a larger-than-OEM design to provide unrivaled strength and reliability in racing and off-road applications.

Product Features:
  • Star washer
  • Fits Ford 9″
  • 3.250″ designs only
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Yukon Gear – Pinion Gear and Thrust Washer for 8" and 9" Ford, Model 20, and 7.25" Chrysler (Part No.33301)

Pinion Gear and Thrust Washer for 8" and 9" Ford, Model 20, and 7.25" Chrysler

from

$4.99
Yukon Gear & Axle manufactures a full line of top quality small parts to complete any job including ring gear bolts, crush sleeves, pinion nuts and washers, axle studs, thrust washers and much, much more. For all your differential small parts needs, look no further than Yukon.

Product Features:
  • Pinion gear thrust washer for Ford 8″, Ford 9″ and Chrysler 7.25″
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Yukon Gear – Standard Open Cross Pin Shaft (.750") for Ford 8", 8.8", 9" and Model 20 (Part No.33332)

Standard Open Cross Pin Shaft (.750") for Ford 8", 8.8", 9" and Model 20

from

$16.99
Yukon Gear & Axle manufactures a full line of top quality small parts to complete any job including ring gear bolts, crush sleeves, pinion nuts and washers, axle studs, thrust washers and much, much more. For all your differential small parts needs, look no further than Yukon.

Product Features:
  • Cross pin shaft for Ford 8″, 8.8″ and 9″ and AMC Model 20
  • Fits standard open differentials only
  • 0.750″ diameter
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Yukon Gear – One (1) Specialty Bearing Race To Adapt Small Bearing Journal Into 3.25" Dropout (Part No.32157)

One (1) Specialty Bearing Race To Adapt Small Bearing Journal Into 3.25" Dropout

from

$51.99
Yukon Gear & Axle manufactures a full line of top-quality small parts to complete any job including ring gear bolts, crush sleeves, pinion nuts and washers, axle studs, thrust washers, and other general maintenance items. For all your differential small parts needs, look no further than Yukon.

Product Features:
  • Carrier race
  • Fits Ford 9″
  • Conversion race to install small bearing carrier into 3.250″ dropout
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Yukon Gear – Trac Loc Internals for 8" & 9" Ford, 31 Spline, Includes Hub & Clutches (Part No.16027)

Trac Loc Internals for 8" & 9" Ford, 31 Spline, Includes Hub & Clutches

from

$487.99
Yukon Gear & Axle clutch kits fit popular Ford diffs outfitted with a Trac Loc style positraction unit feature stout clutch plates, ensuring total traction and long-lasting performance.

Product Features:
  • Spider gear kit
  • Fits Ford 9″ with Trac Loc positraction with 31 spline axles
  • Includes two side gears, four pinion gears, cross pin shaft, clutch hub, roll pin and spider gear thrust washers.
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Yukon Gear – Trac Loc Clutch Guide for 9" Ford (Part No.33250)

Trac Loc Clutch Guide for 9" Ford

from

$4.99
Yukon Gear & Axle manufactures a full line of top quality small parts to complete any job including ring gear bolts, crush sleeves, pinion nuts and washers, axle studs, thrust washers and much, much more. For all your differential small parts needs, look no further than Yukon.

Product Features:
  • Clutch guide
  • Fits Ford 8″ and 9″
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Yukon Gear – Fine Thread Pinion Support Bolt (Aftermarket Aluminum Only) for 9" Ford (Part No.33243)

Fine Thread Pinion Support Bolt (Aftermarket Aluminum Only) for 9" Ford

from

$5.99
Yukon Gear & Axle manufactures a full line of top quality small parts to complete any job including ring gear bolts, crush sleeves, pinion nuts and washers, axle studs, thrust washers and much, much more. For all your differential small parts needs, look no further than Yukon.

Product Features:
  • Pinion support bolt for Ford 9″
  • 3/8″ x 24 thread
  • 1.5″ long
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Yukon Gear – Bearing Race Driver for Ford 9", GM 10.5", & Chrysler 11.5" Differentials (Part No.56019)

Bearing Race Driver for Ford 9", GM 10.5", & Chrysler 11.5" Differentials

from

$219.99
Yukon Gear & Axle offers a full line of top quality differential tools to save time and money.

Product Features:
  • For Ford 9″, GM 10.5″, & Chrysler 11.5″ differentials
  • Fits LM104911 race
  • All-steel construction
  • For accurate installation of bearing races
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Yukon Gear – Trac Loc Clutch Hub For 9" Ford With 28 Splines (Part No.16159)

Trac Loc Clutch Hub For 9" Ford With 28 Splines

from

$139.99
Trac Loc clutch hub for 9″ Ford with 28 splines.

Product Features:
  • Clutch hub
  • Fits Ford 8″ and 9″ 28 spline Trac Loc
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National – Multi-Purpose Bearing (Part No.A-13)

Multi-Purpose Bearing

from

$13.79
Manufactured with premium-grade steel, National taper bearing sets feature crowned raceways and rollers to ensure even load distribution.

Product Features:
  • CONSISTENT PERFORMANCE: Matched cup and cone components ensure consistent performance
  • PREMIUM MATERIALS: Precision manufactured using premium-grade steel for outstanding durability and performance
  • SMOOTH ROTATION: Crowned raceways and rollers for even load distribution
  • OE-STYLE DESIGN: Engineered to meet OE specifications
  • COMPREHENSIVE COVERAGE: Industry-leading coverage for domestic and import applications
  • RIGOROUS TESTING: Comprehensive testing throughout design and development processes by National engineers for quality you can count on
See More

Yukon Gear – Trac-Loc For Ford 8" Wtih 31 Spline Axles – Aggressive Design (Part No.26003)

Trac-Loc For Ford 8" Wtih 31 Spline Axles - Aggressive Design

from

$789.99
The Yukon Dura Grip provides aggressive yet smooth traction to give you the confidence & performance you need. Get longer life and better traction with the heavy duty Yukon Dura Grip Positraction. The Yukon-Trac Loc uses a nodular case, billet side hat, and forged internals for higher strength than stock Trac-Locs. The units use composite clutches for high performance and long life. All units are Rebuildable. Yukon offers a one year warranty against manufacturing defects.

Product Features:
  • Fits Ford 8″ with 31 spline axles
  • Trac Loc positraction
  • Clutch style positraction
  • Aggressive design
  • Internal gears are manufactured using forged 4320 steel and cut to provide stronger teeth
  • Fully rebuildable
  • Assembled in the USA
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Felpro – Differential Carrier Gasket Oval Shaped 10 Bolt Hole Gasket (Part No.RDS 13270)

Differential Carrier Gasket Oval Shaped 10 Bolt Hole Gasket

from

$5.49
Fel-Pro® gaskets are specifically designed for the repair environment to deliver a reliable seal on even the most troublesome applications. Designed for imperfect sealing surfaces and manufactured with proprietary materials, you can count on Fel-Pro for innovative sealing solutions for the real-world repair environment.

Product Features:
  • Meets or exceeds all original equipment specifications
  • Application specific design to ensure a perfect fit
  • Engineered and manufactured specifically for the repair environment
  • Unsurpassed quality you can trust
  • Includes all parts needed to complete the repair
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Yukon Gear – Ford 8" & 9" Standard Open, Ag, & Detroit Locker Ring Gear Bolt (Part No.33058)

Ford 8" & 9" Standard Open, Ag, & Detroit Locker Ring Gear Bolt

from

$5.99
Ford 8″ & 9″ standard Open, AG, & Detroit locker ring gear bolt. 7/16″ head, .925″ long.

Product Features:
  • Ring gear bolt for Ford 8″ and 9″
  • For use with standard open carrier, Auburn Gear limited slip and Detroit Locker
  • 7/16″ head
  • .925″ long
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Yukon Gear – Dana 44, Ford 8" / 9", and Model 20 Side Gear Thrust Washer Replacement (Part No.33283)

Dana 44, Ford 8" / 9", and Model 20 Side Gear Thrust Washer Replacement

from

$5.99
Yukon Gear & Axle manufactures a full line of top quality small parts to complete any job including ring gear bolts, crush sleeves, pinion nuts and washers, axle studs, thrust washers and much, much more. For all your differential small parts needs, look no further than Yukon.

Product Features:
  • Side gear thrust washer for Ford 8″, Ford 9″ and AMC Model 20
  • 0.030″ thick
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Yukon Gear – O-ring for 9" Ford (Part No.30028)

O-ring for 9" Ford

from

$14.99
Yukon Mighty Seals use the latest design and manufacturing technologies to produce a precision fit that seals tight and lasts for years to come.

Product Features:
  • Pinion support O-ring
  • Fits Ford 9″
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Most Popular Differential Pinion Seals for 1977 Mercury Comets

Enhance your 1977 Mercury Comet with one of the 3 Differential Pinion Seals we have in stock, starting at just $12.99.

National – Multi-Purpose Seal (Part No.8181NA)

Multi-Purpose Seal

from

$12.99
National has built a reputation as one of the most respected names in the industry. We have offered premium sealing solutions for more than 75 years. Our design team keeps pace with the industry and provides advanced solutions for today’s vehicles.

Product Features:
  • Design type: spring loaded; multi-lip
  • Temperature range: -40 Deg. F to 225 Deg. F / -40 Deg. C to 107 Deg. C
  • Good low temperature capability
  • Low swell in hydrocarbon fluids
  • Delivers quality and reliable performance for every type of repair
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Yukon Gear – 8" Ford Pinion Seal (Part No.30180)

8" Ford Pinion Seal

from

$24.99
Yukon Mighty Seals use the latest design and manufacturing technologies to produce a precision fit that seals tight and lasts for years to come.

Product Features:
  • Pinion seal
  • Fits Ford 8″
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Motive Gear – Differential Pinion Seal (Part No.7044NA)

Differential Pinion Seal

from

$12.99
Motive Gear offers some of the toughest drive train components on the market today. If you are looking for the largest line of performance ring and pinion gear options available with gear sets in a wide range of ratios for nearly every application, both on and off-road, check out Motive Gear. Motive Gear products can be found in the winner’s circle at racing events worldwide. The superior quality of Motive Gear components is the result of years of racing development, outstanding design and state-of-the-art manufacturing methods. Extensive testing is performed on all products by our in-house engineers.
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Best-Selling 1977 Mercury Comet Front Differential Pinion Bearing

Upgrade your Comet with our best-selling Front Differential Pinion Bearing.

National – Bearing Race (Part No.M86610)

Bearing Race

from

$9.99
Manufactured with premium-grade steel, National taper bearing cups feature crowned raceways to ensure even load distribution.

Product Features:
  • PREMIUM MATERIALS – Precision manufactured using premium-grade steel for outstanding durability and performance
  • SMOOTH ROTATION – Crowned raceways for even load distribution
  • OE-STYLE DESIGN – Engineered to meet OE specifications
  • COMPREHENSIVE COVERAGE – Industry-leading coverage for domestic and import applications
  • RIGOROUS TESTING – Comprehensive testing throughout design and development processes by National engineers for quality you can count on
See More

Top-Quality Differential Bearings for 1977 Mercury Comets

Choose a high-quality OEM or aftermarket Differential Bearing for Mercury Comets and enjoy top-notch performance from $11.99.

National – Multi-Purpose Bearing (Part No.A-13)

Multi-Purpose Bearing

from

$13.79
Manufactured with premium-grade steel, National taper bearing sets feature crowned raceways and rollers to ensure even load distribution.

Product Features:
  • CONSISTENT PERFORMANCE: Matched cup and cone components ensure consistent performance
  • PREMIUM MATERIALS: Precision manufactured using premium-grade steel for outstanding durability and performance
  • SMOOTH ROTATION: Crowned raceways and rollers for even load distribution
  • OE-STYLE DESIGN: Engineered to meet OE specifications
  • COMPREHENSIVE COVERAGE: Industry-leading coverage for domestic and import applications
  • RIGOROUS TESTING: Comprehensive testing throughout design and development processes by National engineers for quality you can count on
See More

Yukon Gear – Pilot Bearing retainer for Ford 9" (Part No.33255)

Pilot Bearing retainer for Ford 9"

from

$11.99
Yukon Gear & Axle manufactures a full line of top quality small parts to complete any job including ring gear bolts, crush sleeves, pinion nuts and washers, axle studs, thrust washers and much, much more. For all your differential small parts needs, look no further than Yukon.

Product Features:
  • Pilot bearing retainer for Ford 9″
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Schaeffler – Bearing – TRB (Tapered Roller Bearing) (Part No.KT13)

Bearing - TRB (Tapered Roller Bearing)

from

$14.99
With advanced load-carrying capacity and compact design, tapered roller bearings are used in wheel bearings, transmissions, differentials, transfer cases and other miscellanous applications. FAG manufacturers over 100 million tapered roller bearings annually.

Product Features:
  • High-precision and High-quality components used in all KITs
  • Coverage of classic and new high-tech solutions for the best system coverage
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Schaeffler – Cone (Part No.KL68149)

Cone

from

$12.99
Our wheel seals are engineered using only the highest-quality materials to meet vehicle manufacturer specificatons. We work with suppliers to design seals that meet FAG’s quality standards. Seals are designed to protect wheel end components from contamination – such as dirt, dust, and moisture – and prevent the loss of grease over the life of the bearing. The specifications for wheel seals are very demanding, and the type required depends on the specific application, position and vehicle class.

Product Features:
  • High-precision and High-quality components used in all KITs
  • Coverage of classic and new high-tech solutions for the best system coverage
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Top Picks for 1977 Mercury Comet Differential Oil

Invest in one of our 5 durable Differential Oil for your 1977 Mercury, knowing you’re getting trusted brands and expert craftsmanship.

Yukon Gear – 3 Qt – 80W90 Conventional Gear Oil with Posi Additive (Part No.15003)

3 Qt - 80W90 Conventional Gear Oil with Posi Additive

from

$57.99
Union 76 gear oil is a conventional non-synthetic 80W90 formulation designed for all types of differentials. This kit includes three quarts of oil and a bottle of Yukon Limited Slip Friction modifier that reduces noise and chatter in clutch driven positraction units and limited slip differentials.

Product Features:
  • Includes three quarts of conventional oil and one 4oz bottle of Yukon positraction additive
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Yukon Gear – 3 Qt – Penzoil 80W90 Conventional Gear Oil (Part No.15002)

3 Qt - Penzoil 80W90 Conventional Gear Oil

from

$44.99
Union 76 gear oil is a conventional non-synthetic 80W90 formulation designed for all types of differentials.

Product Features:
  • Includes three quarts of conventional oil
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Yukon Gear – Redline Synthetic "Shock Proof" Oil with Positraction Additive – 4 Quarts (Part No.15005)

Redline Synthetic "Shock Proof" Oil with Positraction Additive - 4 Quarts

from

$148.99
Redline Heavy Shockproof Gear Oil is formulated to provide lasting protection. This kit includes four quarts of oil and a bottle of Yukon Limited Slip Friction modifier that reduces noise and chatter in clutch driven positraction units and limited slip differentials.

Product Features:
  • Includes four quarts of Redline Shockproof oil and one 4oz bottle of Yukon positraction additive
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Yukon Gear – Redline Synthetic "Shock Proof" Oil – 3 Quarts (Part No.15000)

Redline Synthetic "Shock Proof" Oil - 3 Quarts

from

$99.99
Redline Heavy Shockproof Gear Oil is formulated to provide lasting protection.

Product Features:
  • Includes three quarts of Redline Shockproof oil
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Yukon Gear – Redline Synthetic "Shock Proof" Oil – 4 Quarts (Part No.15004)

Redline Synthetic "Shock Proof" Oil - 4 Quarts

from

$137.99
Redline Heavy Shockproof Gear Oil is formulated to provide lasting protection.

Product Features:
  • Includes four quarts of Redline Shockproof oil
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Rear Differential Cover Gaskets for 1977 Mercury Comets

Make a smart move for your 1977 Mercury Comet with products all priced from $6.49 to $11.99.

Yukon Gear – 9" Ford Gasket (Part No.23012)

9" Ford Gasket

from

$11.99
9″ Ford gasket.

Product Features:
  • Dropout gasket
  • Fits Ford 9″
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Victor Reinz – Differential Cover Gasket (Part No.71-14821-00)

Differential Cover Gasket

from

$6.49
Product Features:
  • Choosing Victor Reinz assures getting OE quality parts in gaskets sets that have the coverage, contents, packaging and electronic cataloging to best meet the needs of the aftermarket.
  • Dana engineering-approved for fit, form and function
  • Meets or exceeds OE specifications
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Top-Rated Differential Brands For Your 1977 Mercury Comet

When it comes to finding the perfect Differential for your 1977 Mercury Comet, Advance Auto Parts has you covered with a wide selection of high-quality OEM and aftermarket options from 12 trusted brands. We carry the most popular Differential brands including Powertrax, National, and Motive Gear, and more, all known for their exceptional customer ratings (average brand rating of 5.0 stars) and competitive prices, as low as $2.79. Purchasing a Differential from us here at Advance Auto Parts is a smart move for both you and your 1977 Mercury Comet, providing peace of mind with parts that meet or exceed OEM standards.

Popular Powertrax 1977 Mercury Comet Differentials

If you’re looking for a top-quality Differential for your 1977 Mercury Comet, Advance Auto Parts has exactly what you need with our selection of Powertrax Differentials. We have 1 Powertrax Differentials in stock for this fitment, all known for their durability and precision fit. With prices starting at just $551.99, you’ll find the perfect Differential for your needs and budget. Powertrax Differentials for the 1977 Mercury Comet come highly rated, with over 1 customer reviews and an impressive average rating of 5.0 stars. Choosing a Powertrax Differential from Advance Auto Parts is a smart move to ensure quality and value for your vehicle.
Differential Lock Assembly
from $551.99
(1)
Differential Lock Assembly
“Installed, no issues, works great.”

Top-Quality National 1977 Mercury Comet Differentials

For those in search of a high-quality Differential for their 1977 Mercury Comet, Advance Auto Parts offers a great selection of National Differentials. With 3 National Differentials in stock, you can trust you’re getting top-tier parts designed for durability and a perfect fit. Prices for these Differentials start at just $12.99, with an average price of $22.92, giving you a range of options to suit your budget. Backed by over 20 customer ratings and an average rating of 4.3 stars, National Differentials provide both reliability and excellent performance. Choosing a National Differential from Advance Auto Parts is a smart investment in your vehicle’s performance and longevity.
Multi-Purpose Bearing
from $13.79
(17)
Multi-Purpose Bearing
“Good quality product”
Shaft Repair Sleeve
from $41.99
(1)
Shaft Repair Sleeve
“Very delicate piece, but came shipped quite safely and not damaged. High quality.”
Multi-Purpose Seal
from $12.99
(2)
Multi-Purpose Seal
“Worked great on this 1966 Mustang w/ 8″ rear end.”

FAQs for 1977 Mercury Comet Differentials

What are the best-selling Differentials for 1977 Mercury Comets?

Out of 339 Differentials that fit 1977 Mercury Comets, the following parts are the top sellers:

What’s the price range for 1977 Mercury Comet Differentials?

The prices of Differentials for the 1977 Mercury Comet range from $1.99 up to $1,211.99 for the most premium parts.

What is the average price of a Differential for a 1977 Mercury Comet?

The average price for Differentials for the 1977 Mercury Comet is $272.28. Keep in mind the variety of part types within our Differential category, where you are likely to find a wide range of prices across a variety of parts and components.

Does Advance Auto Parts sell Differentials for other Mercury Comet model years?

Yes, we carry Differentials for 15 model years of Mercury Comets between 1960 and 1976. The following model years are the most popular for Differential purchases: 1976, 1975, 1974, 1973, 1972, 1971, 1969, 1968, and 1967.

What are the cheapest Differentials for my 1977 Mercury Comet?

The cheapest 1977 Mercury Comet Differentials we carry are:

Does Advance Auto Parts sell Differentials for any other 1977 Mercury models?

Yes. We stock Differentials for 5 other popular 1977 Mercury models. Some of the most popular are 1977 Cougar Differentials, 1977 Grand Marquis Differentials, 1977 Capri Differentials, 1977 Marquis Differentials, and 1977 Monarch Differentials.

What are the top-rated Differentials that fit the 1977 Mercury Comet?

The one 1977 Mercury Comet Differential we have in stock is the Ring Gear Bolt. It costs $1.99.

What types of Differentials do you sell for my 1977 Mercury Comet?

As of 6/2/26, these are some of the most in-demand types of Differentials for a 1977 Mercury Comet:

Can I get help with 1977 Mercury Comet Differential orders?

Contact our customer support team by chat or phone, through the help desk page, where you can find instant answers about Mercury Differentials and more.

What is your return policy for Mercury Comet Differentials?

Advance Auto Parts keeps returns simple. For new Mercury Comet Differentials and accessories, your online orders can be returned, in their original condition, within 45 days. For requirements, see the returns page.