Just looked at a 73 cylinder online and it appears to no longer have that ushaped clip to secure it in the trunk. But it has a rather large threaded not that tightens on the inside of the trunk. Although most places are not in stock, I suppose I should try and find one of those and try it in the opening. I am hoping the previous owner had an issue with the hole, so he hogged it out and installed that 73 version because that would fix the issue. It does not appear to be done in a haphazard manner, so I think the later model might work?? I hope it does. If anybody here has a 73 and up car, maybe they can post a diameter width of the face of their cylinder??