Oldsub is right on with his knowledge. I was at a local restorer and rodder of these trucks this weekend. As always he has about five in various states of disasembly. He was commenting on one of his current builds is going to be a GMC with a V8. He says this works better than the Chevy because he says the radiator support sits lower and he can use a stock fan with a V8. I do believe that I have also heard him say that he has "made" a GMC frame from a Chevy as GMONIZ said.
