1999 GMC Yukon Performance Transmissions

The new design of the B&M Shift Plus Electronic Shift Improver allows you to improve the transmission’s shifting performance without removing the transmission pan or valve body. A simple flip of the switch allows the transmission to operate in the performance mode. Flip it back and you are back to stock! Installs in just minutes, the Shift Plus simply recalibrates your transmission’s hydraulic system electronically for optimum performance and extended life! Select the mode that best suits your application. Reduces slippage and heat! 50 state emissions legal. The Shift Plus shift firmness not only makes driving more fun and pleasurable, but slippage and heat are reduced, extending the life of your transmission!

The B&M Transpak is the next step up from the B&M Shift Improver kit. It has all the features in the Shift Improver kit, plus it provides additional driver manual control (GM TH-400, 350, Ford C-6 and Chrysler Torqueflite only). B&M Transpak kit for 1982-1993 GM TH700R4/4L60 automatic transmissions. Most stock automatic transmissions won’t downshift into low gear above 15 mph, and automatically upshift at a predetermined speed no matter what gear you’re in. With the Transpak, you can downshift at any speed, and you can hold the transmission in first gear to any speed that you want! This is an asset when you’ve got a modified engine, and you want additional RPMs, or you’re towing a trailer or driving heavy loads downhill. Stage 1. Heavy Duty is for street rods, normal passenger vehicles or other heavy duty use. Firmer shift feel but not harsh. Improves transmission performance and life dramatically without loss of comfort and offers normal automatic operation when in Drive. Stage 2 is for Hi-Performance street use. Essentially the same as Heavy Duty mode except shifts are much quicker. Retains full automatic features and standard shift points with selector in Drive. Note: Not for GM 4L60E electronic transmissions.