It is common knowledge when you buy aftermarket sheet metal it needs to be worked to fit. I have some dvd's that were madeby GOODMARK where they replaced every panel on a Chevelle...they had to cut and weld on one of their new fenders to get a perfect fit. I'm not saying it's right but that's how it is. That's why it is usually best to repair originals than to use aftermarket...unless you can't. I even seen in a catalog selling cab corners for 53-56 ford f100's. The ad said
" This panel is junk.Use to make patch panel only.Unusable as a whole panel"