[60-66 Nut]

GMB, the non-synchronized 3 speeds were used in most all 55-66 trucks and even some of the 67-68 trucks too. There were several syncronized 3 speeds used in GM trucks, Saginaw 66-87, Muncie Heavy Duty 69-76, and even a Tremac(yes like Ford) from 76-81. The Saginaw is a good transmission and is probably the most common you will find, but any of them should work. The main difference is they are all longer than the old non-syncro 3 speed, so you will have to either cut your drive shaft or find another one. Also, the Saginaw has a fine spline output shaft like a TH350, so you will need the yoke to go with the trans. They should all have the same bolt pattern to the bell housing and the same input shaft, but the front bearing retainer is bigger on the newer(68 up or so) transmissions, so the hole in the bell housing will need to be machined out or the retainer cut down. Or you could always replace the bell housing with a 68-72 housing. Hope this helps.

60-66 Nut