Seatbelt wiring harness?

[B_derK20]

My new V30 has a 2-wire setup for the seatbelt warning buzzer. My '83 has pristine deluxe belts that I'd like to swap into the '88 but there is only one wire that runs from the fuse panel to the belt retractor. For some reason it's important to me that everything works the way it should including this stupid buzzer lol. Can I make these two different wire harnesses compatable ? I think the single wire just breaks a ground circuit when you pull the belt but I can't figure out how the 2 wire setup works

Thanks in advance!