A 55 3 speed would work just fine. Same basic trans through 67, although the later version (62-up)has a shorter tail shaft. These transmissions are non-syncro in 1st gear and have a 4 bolt side cover. Car transmissions can also be used. The later Saginaw (68-70) trans has a 7 bolt side cover, full syncro, and a fine spline output shaft. It will require some modification to the shift rods as the side cover spacing and arms are different.
Fred
