Im not sure of the specs, but i put a 91 body on a 80 frame, only thing that was different was the body mounts of the frame have a hole cut in the center of them, and they where a different size, so i had to use both my urethane and stock mounts in certain spots. And sorry but i do not remember which one was bigger. The 73 frame could be different all together though, so you may want to go to a parts house and look at both body bushings to give you an idea if they are similar or not.