Steve, there are 3 bolts that hold together the trailer box and the metal frame. The rear bumper is attached to the frame and the 3 bolts are by the spare tire, one is in center and one is by the gas hot water heater. The center and spare tire bolts are broken and the bumper now is lower on the spare tire side by about 1". I have not cut the underliner but it is easy to see and feel that 2 bolts with nuts are broken inside.