LilBill, assuming this is a SM420 GM 4sp, this is no problem. From '55 through '67 GM used the same tranny with an open driveline. All you need to find is the rear coverplate and rear yoke from one of these transmissions. Swap out the rear yoke and coverplate on the earlier tranny and you are done.
Steve O


1950 Chevy 3100
261, 4 speed
Purchased 1977

1964 Pontiac Lemans Convert