72 Demon Seat questions

Thanks for the link. Sorry for the delay in replying. I was in a Mopar junkyard over the weekend and saw a few 72s some with bump outs on the bottom rear seat and some without so maybe it was a changeover year between the manually adjustable and retractable rear seatbelts? I thought they switched to the retractable belts in the rear in 73 but maybe I was wrong.