'51 wheels/later wheels. Same bolt pattern?

[kingscreektrees]

Hi there; I have a '51 3-ton "Maple Leaf" (made in Canada) dually Chev truck. It has 5-bolt rims. I don't think they are the true 'widow-maker' split rims, but no tire centre wants to touch them anyway. Tire centres think they are the widow-makers because they have a locking ring and are therefore not one-piece. Anyway, I want to change to later steel rims, not for looks but to get a one-piece rim and also so I can get more common sizes than the 7.50-20's that are currently fitted. Several people have told me the bolt pattern is the same as some later GM trucks, but no-one can tell me for sure what years and what models are the same. Does anyone know? I think later heavier duty trucks maybe had 21 or 22-inch rims? Thanks for your consideration; Tim