Did the early 70s Camaros use a bumper jack. I was thinking so, and no bodies were bent due to use I would guess. Unless the 73 has a weaker structure in the rear bumper mount than a 77 body, I used the rear bumper mounts in the body all the way until I was ready to start the car. I had to remove the front section to accommodate the engine and all additional items, but the rotisserie allowed me to maintain the height, and added safety. I did however keep blocks under the car throughout the 2 year period in cased of a failure. I had a 78 Camaro fall on me in 1987, and do not want to relive that experience again.