I have a 1967 C10 that I changed from a V8 to a 6 cylinder. When I installed the 6, it bolted up, but the fan was to close to the radiator and you couldn't remove it. After some investigation I discovered that the 6cyl had a different rear crossmember and you just reversed the front motor mounts on the frame. This moved the engine back about inches and put it where it should be. I have heard of people that took out a 6cyl and pyt in a v8 and have had to beat the firewall back to get the distributor cap off. I wonder if this is what happened to you. If it is a 4 speed you need to get the floot pan for the transmission since this will move your transmission also.
Jim
