I also noticed that GMC had leaf springs on the rear of their 1/2 tons while Chevy had the coils. I assume the frames would be different in this area?
I don't know the exact answer to this question. My 1960 GMC came with the coil spring/trailing arm rear suspension. From what I've read I "think" the basic frames are the same for rear coil or leaf springs, just the brackets and perhaps the forward trailing arm crossmember are different.
