GM Transmission Identification Guide

This resource will be on going, and grow as time permits. This resource is for will help my customers and myself get on the same page regarding General Motors transmission styles. It must be understood that the transmissions I am attempting to identify are between 34 and 64 years old. Many parts are interchangeable, and have been changed. So, input shaft grooves and codes will be discussed, for factory correct reasons, they have little actual use for identification purposes.

Many of you have seen the Hurst transmission I.D. chart. I will attempt to bring this chart to life using pictures of actual transmissions.

(GM) Borge-Warner T-10, 9 Bolt Curved Bottom Side Cover

(GM) Saginaw, 7 Bolt Side Cover, 7 Bolt Side Cover

(GM) Saginaw Torque Tube Tailshaft, 81-82 Camaro/Firebird, First Gear Synchronized (Have)

Borge-Warner T-4, Internal Rail (Have)

(GM) Richmond/Borge-Warner Super T-10, 1974 and Later, 9 Bolt Curved Bottom Side Cover

(GM) Borge-Warner Torque Tube Tailshaft, 81-82 Camaro/Firebird, 9 Bolt Side Cover (Have)

(GM) Muncie M20/M21, Early (1963-68), 7 Bolt Side Cover, Transmission Arms Attached with Stud and Nut (Have)

(GM) Muncie M20/M21, Late (1969 and Later), 7 Bolt Side Cover, Transmission Arms Attached with Bolt

(GM) Muncie M22, Late (1970 454 Chevelle), 7 Bolt Side Cover, Transmission Arms Attached with Bolt

3978764 Tailhousing

Here I will attempt to help sort out the confusion on GM shifter arms. This resource is for will help my customers and myself get on the same page regarding General Motors transmission versions.

I am not a transmission pro and this discussion comes from my observations. With part interchangeability, you have to look at the transmission you have and not assume that your transmission has not been apart after 50 to 60 years.

There are 2 different "styles" of  shifter shafts for GM 4 speed transmissions. Muncie 4 speed transmissions used both versions,  Saginaw 4 speeds used bolt style and T-10 and  ST-10 4 speeds use stud style.

The reason the style of the transmission is important is for transmission lever and shifter installation parts identification. There are adapters (our part #242) to allow use of bolt style levers on a stud style

transmission, but stud style levers can not be used on bolt style transmissions without modifications.

The shift levers are attached to the transmission

with a nut. There are flats machined into each side

of the stud. I have found different thread sizes

including 3/8"-24, 3/8"-16 and 5/16".

The rectangular slot at the bottom attaches to the

transmission shift shaft. This slot is shorter than

the bolt style lever.

The shift levers are attached to the transmission

with a 3/8" bolt.

The slotted hole at the bottom is attached to the

transmission, and has clearance for a bolt. The

slot is also longer than the stud style lever.