Frame replacement

[tac246]

I suppose I can always hit a dealer or body shop on a weekday and try to find an answer----but thought I'd try here first and maybe save some running around. Seems to be a lot of great knowledge floating around. I have a 91 GMC 2500 4X4 with great running gear and low mileage but a badly rusted frame. Can anyone tell me what years had the same frame design. I'd like to purchase an earlier or later model GMC, with a good frame, to swap all of the parts to. Thanks for any help----Charlie