You might be shocked how badly body parts fit on cars and trucks back then, even off the factory assembly line. There were no computer designed panels and CAD stuff like they have now. Just steel stamped in a huge press. The fit was "good" but nothing like it is now. I bet the frame can be straightened by welding a tab to the rear rail and pulling it. Replacing a 1/4 can lead to rust issues later on welded portions that can't be reached to be coated or sealed. Once the E coat is burned off, you have bare metal condensing in hidden areas. On top of that, you're not exactly in the desert there. Salt is in the air 24/7. If you can get everywhere to coat the inner part of the welds, then go for it by all means.,,,,BD