Whoa..before this get's out of hand here.

I have a 74 Chally, seat belt interlock system (just posted another tidbit on another post).

"Pink" is on the right track here. There is a seat belt interlock "brain" module that is attached to the dash wiring system. Mine has alway's been an off white color, never seen a 74 black one. I've alway's just disconnected the seat sensor/switches to overide the whole thing.
(That was back in 1976).

If you are a 74 person, you will know what I'm talking about. It's a one year only thing..and I'm still trying to educate the world on how different 74's were....a one year only thing that was not popular.