This article covers the installation of an Aftermarket Tremec T-56 Six-Speed Transmission into my 1975 (Type C-3) Corvette. I bought the transmission from Forte's Parts. It differs from the transmission GM uses in its F-body sport cars. This transmission is made to use the original clutch, bell housing and speedometer plug/cable, out of older sports cars, including most C-3 Corvettes. This conversion is NOT a bolt-in operation. You will need to alter or fabricate several items on the car, in order to install this transmission.

My vehicle is a slightly altered 1975. Originally this car was an L-48 with a 4-speed. After a wreck in 1994, I replaced the small block with a big block and the 5-speed transmission with an automatic. To accept the automatic, I had to modify my existing cross-member. My cross-member was originally welded, so I cut mine inside the frame, welded on end plates and now mount each side with four bolts. The specific way I modified mine is not mandatory for this installation, so you can modify yours anyway you please, as long as it will accept this transmission and can be removed from the vehicle. Also, I eliminated the cable (on manual transmission cars), which eliminated you from removing your ignition key without first putting the car in reverse. This cable was attached to the shift arm of the old transmission, but the new transmission has an internal shifting rail, so there is no place for attachment. I can now remove my key, no matter what gear, including neutral.

IMPORTANT NOTE: The installation of this transmission was done bolted to the motor and installed as a unit. I did not put it in by itself, with the engine already installed. Therefore, I cannot say that you will be able to install it separately, although it does appear highly possible to do so. You would need to, at the least, remove the shifter from the transmission and drop the back of the engine down enough to allow insertion of the input shaft into the adapter plate and bell housing. You may need to remove the fan blade and/or distributor and loosen the motor mounts.

Major Items Needed For This Swap

· After market Tremec T-56 Six Speed Transmission (Approx. $2K)
· Custom-built transmission cross-member. (Approx. $200.00)
· Turbo 350 transmission output shaft yoke for Corvette (Approx. $170.00)
· Driveshaft shortened and balanced (Approx. $50)
· Console cover plate modification
· New shifter arm or modify your old one.


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