Hy GasHog. welcome, what size of truck are we asking about? The largest Canadian Chevrolet trucks, the 17 series (Maple Leaf 3ton) were GMC powered. I am sure there were hundreds of GMC engines swapped into both Chevrolet trucks and cars back in the day. As my experience is with Canadian trucks I have no personal knowledge of the differences in sheet metal between the Canadian and American trucks, I assume there are differences to accommodate the longer GMC engine. Good luck with your project.
