On the left of this page is a link to Tech Tips. There is great info on T-5s there and even a link to the Stovebolt site. It will help you sort out the T-5 choices including using an S-10 tail housing to locate the shifter to a better place and which ones will bolt to your bell housing. Patrick's used to adapt Saginaws to closed driveline and sell a 3.55 gear set. Patrick is gone but the info is out there somewhere. He sold a nice shifter for a T-5 too.
My '53 pickup has a '57 GMC 270. The bell housing is the same as a '55 pickup and locates in the same place. I first went to open driveline with a Saginaw 4 speed. I went with a 3.55 Dana 44 limited slip from a '68 GMC 4x4, I welded new spring perches on it. If you go with open driveline and the old rear end I'm not sure how the hinged mounts on the springs will work. I lucked out and was able to pull a driveshaft out of a parts pile. Later I installed a T-5 from an S10, can't remember which one. I do remember that I found a clutch plate that fit the input shaft and worked with a pressure plate that bolted up. I was a parts man back then and could go through boxes till I found what worked. The T-5 input shaft is 3/8" too long on the very front. It can be cut. Since the bolt pattern on my T-5 didn't fit I made a 3/8" adapter plate and left the shaft long. I had to carve on the tranny case some because a couple of bolts were too close. I would not do it that way again but it has been working for about 20 years. My Ratios are not perfect low gear is a bit low but comes in handy for hauling heavy loads up the hill I live on. Second is a bit high for taking off from a stop most of the time. A little rear end gear change would fix that. It cruses between 70 & 75 at around 2,200 rpm and 3,000 rpm is 90. Tire size is important.
"I wonder if God created man because he was disappointed in the monkey?" Mark Twain
