Can someone tell me my bolt pattern?

Welcome to FABO!!

People like to play...sorta like hanging out in the garage and razzing each other.

That era was mostly 5 on 4.5". Certainly someone could have swapped in a different rear. Tolerances were a little loose back then and rears can be off by as much as three quarters of an inch. Like @doug 371 said, probably used washers as a spacer.