43 Jr

That is indeed 43jr #1. It was buried behind Petty's shop for years, and then when a lot of stuff was unearthed for new construction, it was given to the late founder of the junk yard where you saw it. The man who owned the junk yard was good friends with the Petty family, and a very competitive drag racer in his day. His descendants still sell stuff out of the yard, but they never say "We've got 43jr, wanna see it?" Just like they did you, they will say what the carcass is if someone recognizes it and asks. It has been laying in that spot for several decades, and 43jr #2 is restored and supposedly in the Chicago area. Props to you for not disclosing the location. They are very private people, and not just anybody gets in the junk yard anymore.