I need a dash harness for my 70 challenger. Friend will give me one for a 1971 challenger. What is the difference, and can I run a 71 dash harness? Not worried about correct or OE restoration. Thanks guys!

Surely, somebody knows the difference?

I agree you could probably interchange the two. I'm sure there's minor differences, although nothing that would fry anything. If you're really worried about it, you could compare the wiring diagrams in both the FSMs. There's a few dozen wires, photocopy both diagrams and mark off each wire with a highlighter. It shouldn't be that bad. Good luck.

Just look at the wiper switch plug. If both cars have a two speed wiper motor or both have a vaiable speed wiper motor than you are OK if the wiper motor and harness are diffiferent then you will need a wiring diagram to correct the situation. In otherwords:
The harness is different if you have a two speed wiper motor or a variable speed motor.

It makes a difference if you have a ralley dash or not. In either case you can work through the differences. Look for oil pressure gauge rather than oil light and clock leads and tach leads. Get a wiring diagram. You'll be OK.