GMC & Chevrolet Built their own trucks back in the days before about 1970. They are not the same in many ways, Engines was a big difference, but on some of the older ones I have heard tell that even the entire front clip is not the same.
GMC built trucks to work, and sold most truck day in those days to folks who worked trucks. Chevy on the other hand built trucks for the family, using a lot of non truck items like car engines.
But if you planning on hot rodding, I hear tell that the GMC inline engine is a better place to start than a Chevy, but if your tossing the engine in favor of a small block V8, well even a Dodge makes a good project. I would have said ford but you all know what happen when you type the four letter f-word.
