Ken i call the saginaw trans used in 70's chevy trucks and mid size cars the big saginaw. this is not the little three speed in late 50's trucks and cars. the older trans was used alot in drag cars but they are kinda weak.
Back in the late 60's and early 70's we ran a 2 speed trans . It was a side shift out of a Chevy truck . It was very short and used the same main case as a t 10 4 speed . I think it was a t 89 trans . Not 100 percent shure though . If you really want to do something fun why don't you try to find an old clutchflite trans !