Check Ebay motors for oldtime service manuals and operators' manuals. There's usually a bunch of them out there. The HydraMatic was used in a lot of cars besides GM, even Lincoln, Hudson, and Nash used them in some applications. Pontiac, Oldsmobile, and Cadillac used one version or another from the late 1930's to the mid-1960's. The 38 and 39 Oldsmobile had a 4-speed auto, but used a manual clutch. By 1940, they added the fluid coupling and started calling it the HydraMatic. WW II trucks and some tanks used the same transmission, (Cadillac engine in the tank) and there was a double-transmission rig with one trans on top of another that used a torque splitter to adapt to an engine too powerful for one Hydramatic to handle. I don't remember the application on that one.
I grew up around one of the two shops in Nashville that began working on automatics in the late 1940's. The other guy besides Dad who dit transmission work had been a tank mechanic in WW II.
Jerry
