Hi santagary. Please post an introduction in the Welcome Centre, if you have not already.
You should probably start a new thread in the Driveline forum with your questions about a PG swap. Not many people will see your question tacked onto a thread about an engine swap.
Powerglides were never offered in pre-1960 GMC's. Starting in 53 Hydramatics were available in GMC's, and then in 54 for Chevy trucks. I don't know if a cast iron 'Glide from a 235 Chevy car will fit a GMC or not. Good luck.
