Very similar story to one above. Driving along with my wife in the GP. All of a sudden heard a hell of a racket from the rear of the car. My wife is panicing, and all I could do was laugh. I knew the bumper was starting to sag. Well, it sagged completely off on the passenger side and was dragging along behind us. I found some electrical wire in the trunk, no, not part of the cars wiring, LOL, pulled the bumper up and wired it on so I could get the car home.
Its the same GP in my avatar. Its currently sitting on jack stands with the gas tank and muffler removed. Rear bumper is in the garage. Frame rails were swept up and thrown away. Yeah, literally swept up.
Not much left of drivers side, even less of passenger side. I'm fabbing up new 2x3 square tube rails. Rest of frame is pretty solid. Trunk floor is excellent shape, the body mount locations welded to the trunk floor are non existant tho. I've fabbed up the rearmost drivers side mount to weld to the trunk floor. It looks pretty close to stock, as there was some of the old left to copy. The mount right behind the wheel was just two strips of rusty metal loosely attached to the trunk floor. I'll be making a new mount there and unless I get real lucky, it will look nothing like the original, since I have nothing to copy but those two strips. Haven't looked at passenger side yet. The top section of the frame rail is still there blocking the view. Thats all thats left of the frame tho. That and a piece of tubing I bolted to the truck floor temporarily to bolt the bumper to so I could still use the car if need be. Those days are gone now, so its rebuild it the right way time. Some rust in the lower quarter, easily patched with welded in sheet metal. Floors are pretty solid with just a couple pin holes in front of the passenger seat. All solid up front.