What are having problems with? I have a few Challengers and the entire wiring for the whole car fits on two pages of the service manual. Really nice compared to the hundreds of pages for newer cars.

Its in the cluster of wires behind the dash. One wire was baked all the way through. Don't know where it came from or went to

A wiring diagram isn't going to help yet because you would have to know which wire you're looking at. The best plan is to dig that wire out and follow it to both ends and see what it connects to.

What doesn't work? How fat is that wire? That will show how much current it is expected to handle and the type of circuit it might be for.