I installed a 1969 C10 body on a 1976 K20 frame. It took a lot of changes to make it fit. The wheel base is 4 inches longer and has to be shortened. the rise on the frame is under the cab instead of under the bed. To get the body to sit close to the right height i cut a section out of both sides of the frame and switched them side to side to move the rise closer to the back. I took the cab mounts off of the earlier model and mounted them to the 76 frame. I had to fabricate mounts for the radiator support. This being said I would do it again because I like the way it turned out.