My 1966 mustang looks like it might have had a minor hit in the rear at one time. The front edge of the brace next to the gas tank that goes between the rear frame rails is straight across. The bottom edge of the taillight panel is straight across. The top of the taillight panel lines up fine with the trunk lid. Where the rear floor cross member attaches to the taillight panel there is a slight curve in toward the front of the car in the middle. Is this correct?

 

It was interesting to read this. I have a 67 project coupe. I had purchased a new rear valance with the exhaust cutouts to replace the one on the car. When I went to install it, I noticed the top edge did not sit flush against the body. It also has a slight curve in toward the front of the car in the middle. The only way to screw in the new valance is to push the top center up against the body. I just assumed the car backed into something, and pushed the sheet metal in slightly. I would be interested to hear if there are similar situations out there, or do we just happen to have cars that have been damaged at some point.