I believe there is no difference between the 1/2 and 3/4t boxes. I've rebuilt two 1/2 ton boxes. It's fairly straight forward with the exception of removing a few of the bushings which can be a pain. The Stovebolt website will provide you with a bunch of resources. If the bushings look ok, I'd skip them. It's typically the bearings and gunk buildup that makes them steer hard. Once they are rebuilt, there's no need for power steering. Seriously. Here's a pic of the suburban box tore down
http://gallery.mac.com/patrick.plummer#100287/DSCN1460&bgcolor=blackhttp://gallery.mac.com/patrick.plummer#100287/DSCN1457&bgcolor=blackAnd the pooched bearing
http://gallery.mac.com/patrick.plummer#100287/DSCN1462&bgcolor=blackHere is a copy of the 1954 shop manual for procedures here:
http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0901.htmlAs for replacment parts and a rebuild kit, Patrick's in Arizona seemed to be the cheapest for my latest rebuild if I recall. I think that answered all your questions.