1978 Mercury Cougar Differentials

Keep Your 1978 Mercury Cougar in Top Shape with Quality Differentials

Whether you’re repairing or upgrading your Differential, using high-quality parts is key to keeping your 1978 Mercury Cougar looking sharp and performing at its best. At Advance Auto Parts we carry a wide selection of dependable options, including Differential Bearings, Rear Differential Cover Gaskets, and Differential Pinion Seals. 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, Powertrax, and FELPRO. For example, National Differentials start at just $10.49 with an average 4.3 star rating. Powertrax and FELPRO offer similar pricing and quality, backed by strong customer feedback. With over 564 reviews and a solid 5 star average, you can shop with confidence knowing other Mercury Cougar owners approve.

Competitive Prices and Extensive Inventory

The average price for a 1978 Mercury Cougar Differential at Advance Auto Parts is around $266.58, with a range that starts at $1.99 and goes up to $1,566.99. With 326 options in stock from 13 trusted brands, finding the right fit is easy. Popular picks like 3 Qt – 80W90 Conventional Gear Oil With Posi Additive, Bearings, and Bearings start at just $6.99 and offer a great balance of form and function.

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 1978 Mercury Cougar in peak condition, inside and out.

Essential 1978 Mercury Cougar Differentials

Motive Gear – Differential Gear Install Kit (Part No.F9IK)

Differential Gear Install Kit

from

$33.99
Product Features:
  • MINI INSTALL KIT FORD 9″
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Richmond Gear – Differential Cross Shaft (Part No.CSPF9)

Differential Cross 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 a two year 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 – Ford 9" Nodular Daytona Style Pinion Support (Part No.32164)

Ford 9" Nodular Daytona Style Pinion Support

from

$175.99
Product Features:
  • Fits Ford 9″ with 28 spline pinion
  • Larger inner pinion bearing reduces gear deflection under high load
  • Nodular iron
  • Does not include races
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Valvoline – SynPower Transmission & Differential Gear Oil: Full Synthetic 75W-140, 1 Gallon (Part No.887344)

SynPower Transmission & Differential Gear Oil: Full Synthetic 75W-140, 1 Gallon

from

$69.99
Valvoline SAE 75W-140 Full Synthetic Gear Oil provides the ultimate gear protection in hypoid rear differentials and non-synchronized manual transmissions. Engineered to outperform, our formulation provides exceptional high and low temperature protection and excellent thermal stability, especially in demanding driving situations such as towing and off-roading. It contains an extreme pressure additive for better load carrying capacity and wear resistance, a limited slip additive for optimal clutch pack performance, and an anti-foaming agent for better lubrication and service life. It’s recommended for conventional rear axles and transmissions requiring EP gear lubes under high speed, high load, high torque and high horsepower conditions.

Product Features:
  • EXCEPTIONAL HIGH AND LOW TEMPERATURE PROTECTION ranging from -22F to 390F degrees
  • REDUCES CHATTERING AND PROTECTS GEAR TEETH from oxidation, rust, and wear
  • FIGHTS CORROSION AND RUST with emulsifying agents and safeguards against impurities, oxidation and thermal breakdown
  • MEETS THE DEMANDS OF CONVENTIONAL AND LIMITED SLIP REAR DIFFERENTIALS where API GL-5 is specified, as well as non-synchronized manual transmissions that require API GL-4
  • MEETS OR EXCEEDS PERFORMANCE REQUIREMENTS for Ford M2C-192A, GM 12346140, Chrysler MS-8985 and API GL-5
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Yukon Gear – One (1) Specialty Bearing Race To Adapt Small Bearing Journal Into A 3.250" Dropout (Part No.32157)

One (1) Specialty Bearing Race To Adapt Small Bearing Journal Into A 3.250" Dropout

from

$51.99
One (1) specialty bearing race to adapt small bearing journal into a 3.250″ dropout. This adapter allows the use of a 28 or 31 spline carrier, positraction or locker in a 3.250″ dropout. This is a perfect solution if you are currently running 28 or 31 spline axles but are looking to upgrade to 35 spline later, or are stepping down from 35 spline but don’t want to buy a new dropout.

Product Features:
  • Carrier race
  • Fits Ford 9″
  • Conversion race to install small bearing carrier into 3.250″ dropout
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Motive Gear – Performance Differential Ring and Pinion (Part No.F880340)

Performance Differential Ring and Pinion

from

$272.99


Product Features:
  • R&P FORD 8″ – 3.40 RATIO
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Motive Gear – Differential Bearing Kit – Timken (Part No.RA310RT)

Differential Bearing Kit - Timken

from

$106.99
Motive Gear Differential Bearing Kits Include Front & Rear Pinion Bearing, Pinion Seal, Carrier Bearings, Pilot Bearing Where Applicable, Gear Marking Compound, Crush Sleeve, Pinion Nut, Brush, Thread Locking Compound And Cover Gasket Or Rtv

Product Features:
  • KIT BRG & SEAL FORD 8″
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USA Standard Gear – Master Overhaul Kit for the Ford 8" Differential (Part No.37028)

Master Overhaul Kit for the Ford 8" Differential

from

$275.99
USA Standard Master Overhaul kits let you finish your install with confidence. This kit uses Koyo bearings and races. Included are carrier bearings and races, pinion bearings and races, pinion seal, complete shim kit, ring gear bolts, pinion nut, crush sleeve (if applicable), oil baffles and slingers (if applicable), threading locking compound, marking compound with brush and gasket.

Product Features:
  • Fits Ford 8″
  • Uses Koyo bearings and races
  • Included are carrier bearings and races, pinion bearings and races, pinion seal, complete shim kit, ring gear bolts, pinion nut, crush sleeve, thread locker, marking compound with brush and gasket.
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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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Yukon Gear – 9" Ford Pinion Nut, 35 Spline Large Pinion Oversize (Part No.33161)

9" Ford Pinion Nut, 35 Spline Large Pinion Oversize

from

$26.99
9″ Ford pinion nut, 35 spline Large pinion oversize.

Product Features:
  • Pinion nut
  • Fits Ford 9″ with 35 spline pinion
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Felpro – Differential Carrier Gasket Oval Shaped 10 Bolt Hole Gasket (Part No.RDS 55074)

Differential Carrier Gasket Oval Shaped 10 Bolt Hole Gasket

from

$8.49
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
  • Unsurpassed quality you can trust
  • Validated for fit, form and function
  • Each Fel-Pro gasket, no matter how small, is engineered to exacting standards with proprietary design, engineering and manufacturing processes
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Yukon Gear – O-Ring For 9" Ford (Part No.30028)

O-Ring For 9" Ford

from

$14.99
O-ring for 9″ Ford.Yukon Mighty seal.

Product Features:
  • Pinion support o-ring
  • Fits Ford 9″
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Motive Gear – Differential Pinion Shim Kit (Part No.WAA4663)

Differential Pinion Shim Kit

from

$15.99
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 Install Kit For Ford 7.5" Differential (Part No.13039)

Pinion Install Kit For Ford 7.5" Differential

from

$184.99
Yukon Pinion installation kits are a terrific solution for gear installation on lower mileage vehicles where the carrier bearings & races can be reused. This kit uses Timken bearings and races along with a high quality pinion seal and small parts. Included in this kit are the pinion bearings and races, pilot bearing (if applicable), crush sleeve (if applicable), complete pinion shim kit, thread locker, and marking compound with brush. Yukon does extensive research for each application to make sure your kit will arrive with all the correct parts you need to install your pinion gear.

Product Features:
  • Fits Ford 7.5″
  • Included are pinion bearings and races, pinion seal, pinion nut, crush sleeve, complete pinion shim kit, and marking compound with brush.
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National – Multi Purpose Seal (Part No.51098)

Multi Purpose Seal

from

$7.29
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:
  • Low swell in hydrocarbon fluids
  • Design type: spring loaded; multi-lip
  • Provides good low temperature capability
  • Temperature range: -40°F to 225°F; -40°C to 107°C
  • Delivers quality and reliable performance for every type of repair
See More

Yukon Gear – Dropout Housing Stud For Ford 8" & 9" (Part No.32338)

Dropout Housing Stud For Ford 8" & 9"

from

$7.99
Product Features:
  • Housing stud
  • Fits Ford 8″ and 9″
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USA Standard Gear – Standard Spider Gear Set For Ford 9", 31 Spline, 4-Pinion Design (Part No.39018)

Standard Spider Gear Set For Ford 9", 31 Spline, 4-Pinion Design

from

$249.99
Product Features:
  • Spider gear kit
  • Fits Ford 9″ 31 spline open differential
  • Includes two side gears, four pinion gears, cross pin shaft, roll pins and spider gear thrust washers.
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Yukon Gear – Side Gear And Thrust Washer (0.750" Shaft) For 8.8" Ford (Part No.33298)

Side Gear And Thrust Washer (0.750" Shaft) For 8.8" Ford

from

$6.99
Side gear thrust washer (0.750″ shaft) for 8.8″ Ford.

Product Features:
  • Side gear thrust washer for Ford 8.8″
  • 0.750″ diameter cross pin shaft applications only
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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
Fine thread pinion support bolt (aftermarket aluminum only) for 9″ Ford.

Product Features:
  • Pinion support bolt for Ford 9″
  • 3/8″ x 24 thread
  • 1.5″ long
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National – Shaft Repair Sleeve (Part No.99199)

Shaft Repair Sleeve

from

$37.99
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:
  • Designed to repair damaged, grooved or worn shafts
  • Durable stainless steel construction for corrosion-free sealing surface that surpasses most original shaft specifications
  • Ideal for a shaft where indications of seal wear, such as tracks or grooves have developed
  • Ultra-thin construction (0.01/0.25mm wall thickness) allows original seal size to be used with minimal additional lip loading
  • Easy to install with removable flange and installation tool
  • Installation tool reduces sleeve distortion and allows for installation without removal from the shaft
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Motive Gear – Differential Pinion Solid Spacer Kit w/Shims (Part No.SS9)

Differential Pinion Solid Spacer Kit w/Shims

from

$45.99
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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FAG US – CONE (Part No.KM88048)

CONE

from

$19.49
CONE

Motive Gear – Nodular Differential Housing (Part No.26325)

Nodular Differential Housing

from

$533.99


Product Features:
  • NODULAR HOUSING 9″ FORD 3.25″ BORE
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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 – Outer Oil Slinger For Ford 7.5", 8.8", 9", 10.25" (Part No.33022)

Outer Oil Slinger For Ford 7.5", 8.8", 9", 10.25"

from

$8.99
Replacement outer oil slinger for Ford 7.5″, 8.8″, 9″, 10.25″, Nissan Titan rear, Dana 44 Rubicon & 44 JK non-Rubicon.

Product Features:
  • Outer oil slinger for Ford 10.25″, 7.5″, 8.8″ and 9″ also Jeep JK and Nissan Titan rear
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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
Trac Loc clutch guide for 9″ Ford.

Product Features:
  • Clutch guide
  • Fits Ford 8″ and 9″
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Powertrax – Grip PRO Traction System (Part No.GT109028)

Grip PRO Traction System

from

$496.99
For vehicles that are driven daily, the Powertrax 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 Powertrax No-Slip locker easily installs in to your differential carrier using basic tools and without affecting your ring and pinion settings. Powertrax Grip-Lok, Lock-Right Lockers and No-Slip Traction Systems automatically provide 100% traction on-demand, under the toughest circumstances. The Powertrax Grip-Pro and Grip-LS performance limited slips offer smooth dependable torque transfer and traction for the best of both worlds!
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Yukon Gear – Short Cross Pin Shaft Without Block For 9" Ford (Part No.33335)

Short Cross Pin Shaft Without Block For 9" Ford

from

$11.99
Short cross pin shaft without block for 9″ Ford.

Product Features:
  • Cross pin shaft
  • Fits Ford 9″
  • Short design
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Most Popular Differential Bearings for 1978 Mercury Cougars

Enhance your 1978 Mercury Cougar with one of the 4 Differential Bearings we have in stock, starting at just $6.99.

National – Bearings (Part No.LM102949)

Bearings

from

$19.49
National Oil Seals & Bearings offer a full line of premium oil seals and bearings.

Product Features:
  • Premium bearing design matches OEM specifications
  • Precision manufactured using premium-grade steel for outstanding durability and performance
  • Crowned raceways and rollers to ensure even load distribution for maximum life
  • Industry leading coverage
  • Professional technicians know they can depend on National
See More

National – Bearings (Part No.A-18)

Bearings

from

$18.49
National Oil Seals & Bearings offer a full line of premium oil seals and bearings.

Product Features:
  • Premium bearing design matches OEM specifications
  • Precision manufactured using premium-grade steel for outstanding durability and performance
  • Crowned raceways and rollers to ensure even load distribution for maximum life
  • Industry leading coverage
  • Professional technicians know they can depend on National
See More

National – Bearings (Part No.LM102910)

Bearings

from

$6.99
National Oil Seals & Bearings offer a full line of premium oil seals and bearings.

Product Features:
  • Premium bearing design matches OEM specifications
  • Precision manufactured using premium-grade steel for outstanding durability and performance
  • Crowned raceways and rollers to ensure even load distribution for maximum life
  • Industry leading coverage
  • Professional technicians know they can depend on National
See More

Yukon Gear – Pilot Bearing Retainer For Ford 9" (Part No.33255)

Pilot Bearing Retainer For Ford 9"

from

$11.99
Pilot bearing retainer for Ford 9″.

Product Features:
  • Pilot bearing retainer for Ford 9″
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Best-Selling 1978 Mercury Cougar Rear Differential Cover Gaskets

Upgrade your Cougar with one of our 2 best-selling Rear Differential Cover Gaskets.

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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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

$21.79
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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Top-Quality Differential Pinion Seals for 1978 Mercury Cougars

Choose a high-quality OEM or aftermarket Differential Pinion Seal for Mercury Cougars and enjoy top-notch performance from $7.29.

National – Multi Purpose Seal (Part No.7044NA)

Multi Purpose Seal

from

$15.79
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:
  • Low swell in hydrocarbon fluids
  • Design type: spring loaded; multi-lip
  • Provides good low temperature capability
  • Temperature range: -40°F to 225°F; -40°C to 107°C
  • Delivers quality and reliable performance for every type of repair
See More

National – Multi Purpose Seal (Part No.51098)

Multi Purpose Seal

from

$7.29
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:
  • Low swell in hydrocarbon fluids
  • Design type: spring loaded; multi-lip
  • Provides good low temperature capability
  • Temperature range: -40°F to 225°F; -40°C to 107°C
  • Delivers quality and reliable performance for every type of repair
See More

Yukon Gear – Pinion Seal For ’61-’85 9" Ford (Part No.30137)

Pinion Seal For '61-'85 9" Ford

from

$17.99
Pinion seal for ’61-’85 9″ Ford. 3″ OD.Yukon Mighty seal.

Product Features:
  • Pinion seal
  • Fits 1961-1985 Ford 9″
  • 3.00″ O.D.
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FAG US – SHAFT SEAL (Part No.SS2934)

SHAFT SEAL

from

$19.79
SHAFT SEAL

Motive Gear – Differential Pinion Seal (Part No.7044NA)

Differential Pinion Seal

from

$12.99
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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Top Picks for 1978 Mercury Cougar Front Differential Pinion Bearings

Invest in one of our 3 durable Front Differential Pinion Bearings for your 1978 Ford, knowing you’re getting trusted brands and expert craftsmanship.

National – Bearings (Part No.M88048)

Bearings

from

$15.99
National Oil Seals & Bearings offer a full line of premium oil seals and bearings.

Product Features:
  • Premium bearing design matches OEM specifications
  • Precision manufactured using premium-grade steel for outstanding durability and performance
  • Crowned raceways and rollers to ensure even load distribution for maximum life
  • Industry leading coverage
  • Professional technicians know they can depend on National
See More

National – Bearings (Part No.M88010)

Bearings

from

$10.49
National Oil Seals & Bearings offer a full line of premium oil seals and bearings.

Product Features:
  • Premium bearing design matches OEM specifications
  • Precision manufactured using premium-grade steel for outstanding durability and performance
  • Crowned raceways and rollers to ensure even load distribution for maximum life
  • Industry leading coverage
  • Professional technicians know they can depend on National
See More

Driveworks – Taper Bearing Cone (Part No.S-M-88048)

Taper Bearing Cone

from

$11.49
Value-priced bearing meets all cataloged application requirements.

Product Features:
  • Brand may vary by location
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Differential Oil for 1978 Mercury Cougars

Make a smart move for your 1978 Mercury Cougar with products all priced from $57.99 to $148.99.

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
3 Qt. Penzoil 80W90 conventional gear Oil. W/ bottle of Posi additive.

Product Features:
  • Includes three quarts of conventional oil and one 4oz bottle of Yukon positraction additive
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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 Synthetic “Shock Proof” Oil with positraction Additive. 4 Quarts.

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 Synthetic “Shock Proof” Oil. 3 Quarts.

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 Synthetic “Shock Proof” Oil. 4 Quarts.

Product Features:
  • Includes four quarts of Redline Shockproof oil
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Top-Rated Differential Brands For Your 1978 Mercury Cougar

When it comes to finding the perfect Differential for your 1978 Mercury Cougar, Advance Auto Parts has you covered with a wide selection of high-quality OEM and aftermarket options from 13 trusted brands. We carry the most popular Differential brands including Powertrax, FELPRO, and National, and more, all known for their exceptional customer ratings (average brand rating of 4.7 stars) and competitive prices, as low as $8.49. Purchasing a Differential from us here at Advance Auto Parts is a smart move for both you and your 1978 Mercury Cougar, providing peace of mind with parts that meet or exceed OEM standards.

Popular Powertrax 1978 Mercury Cougar Differentials

If you’re looking for a top-quality Differential for your 1978 Mercury Cougar, Advance Auto Parts has exactly what you need with our selection of Powertrax Differentials. We have 2 Powertrax Differentials in stock for this fitment, all known for their durability and precision fit. With prices starting at just $444.99 and an average cost of $498.49, you’ll find the perfect Differential for your needs and budget. Powertrax Differentials for the 1978 Mercury Cougar come highly rated, with over 2 customer reviews and an impressive average rating of 4.7 stars. Choosing a Powertrax Differential from Advance Auto Parts is a smart move to ensure quality and value for your vehicle.
Lock Right Locker
from $444.99
(1)
Lock Right Locker
“Fast service and the right part.”
No-Slip Traction System
from $551.99
(1)
No-Slip Traction System
“Installed, no issues, works great.”

Top-Quality FELPRO 1978 Mercury Cougar Differentials

For those in search of a high-quality Differential for their 1978 Mercury Cougar, Advance Auto Parts offers a great selection of FELPRO Differentials. With 1 FELPRO 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 $8.49, giving you a range of options to suit your budget. Backed by over 9 customer ratings and an average rating of 4.6 stars, FELPRO Differentials provide both reliability and excellent performance. Choosing a FELPRO Differential from Advance Auto Parts is a smart investment in your vehicle’s performance and longevity.
Differential Carrier Gasket Oval Shaped 10 Bolt Hole Gasket
from $8.49
(9)
Differential Carrier Gasket Oval Shaped 10 Bolt Hole Gasket
“Right fit the first time.”

FAQs for 1978 Mercury Cougar Differentials

What are the best-selling Differentials for 1978 Mercury Cougars?

Out of 326 Differentials that fit 1978 Mercury Cougars, the following parts are the top sellers:

What’s the price range for 1978 Mercury Cougar Differentials?

The prices of Differentials for the 1978 Mercury Cougar range from $1.99 up to $1,566.99 for the most premium parts.

What is the average price of a Differentials Differential for a 1978 Mercury Cougar?

The average price for Differentials for the 1978 Mercury Cougar is $266.58. 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 Cougar model years?

Yes, we carry Differentials for 33 model years of Mercury Cougars between 1967 and 2002. The following model years are the most popular for Differential purchases: 2002, 2001, 2000, 1999, 1997, 1996, 1995, 1994, and 1993.

What are the cheapest Differentials for my 1978 Mercury Cougar?

The cheapest 1978 Mercury Cougar Differentials we carry are:

Does Advance Auto Parts sell Differentials for any other 1978 Mercury models?

Yes. We stock Differentials for 4 other popular 1978 Mercury models. Some of the most popular are 1978 Grand Marquis Differentials, 1978 Zephyr Differentials, 1978 Marquis Differentials, 1978 Monarch Differentials, and 1978 Bobcat Differentials.

What types of Differentials do you sell for my 1978 Mercury Cougar?

As of 4/10/25, these are some of the most in-demand types of Differentials for a 1978 Mercury Cougar:

Can I get help with 1978 Mercury Cougar 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 Cougar Differentials?

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