The ball bearings on your truck are designated B01 (outer) and B52 (inner). The outer bearing can be replaced by a tapered roller bearing 09074 cone and 09207 cup (Timken #'s). I think 70's Camaros use these. That is why when you go with 5 lug disc rotors you only need to sleeve your spindle for the inner bearing. The Camaro, Monte Carlo, etc outer bearings fit.
No one I have found except for a company in Japan named MBS makes a replacement tapered roller for the inner bearing. Its MBS909052R The only other choices on the inner are to sleeve the spindle or bush the hub.
Its just easier to buy the bearing sets from one of the suppliers. I got mine from CPP when they had some on sale on Ebay. Incidentally, I was surprised to find no markings or ID on these bearings whatsoever.
'53-'57 Corvette front wheel bearings are same as our 1/2 tons. Here is a message from one of their forums. I searched for all the companies mentioned and either couldn't find them or they were as expensive as anyone else.
http://forums.corvetteforum.com/c1-and-c2-corvette...