Back in the 70's I usta' build those things. Jerry is right. In a wreck they pretty much disintegrate. My first job at 'Bago was running the drill press drilling holes in the 1'' X 2'' thin wall tubing used to build the "box" that is the motor home. A little stamped aluminum skin on the outside, foam insulation between the tubes & paneling on the inside and there you have it.