John, check out the tech tip on T5 into an Art Deco.
http://www.stovebolt.com/techtips/tranny/sandoval/index.html Call Buffalo Enterprises and have an adpater made for $125 and it will be a quick swap.
That is how I put an SM465 in my 39. I, will be doing a swap into a 46 half ton soon also. Feel free to post specific questions or PM me.
The Patricks Saginaw shifter is real expensive, you could do an entire T5 swap for the cost of Patricks Shifter.
50GMC, Art Deco trucks have the pedals bolted to the bellhousing not the frame and a smaller diameter bearing retainer hole (index).
