Door removal 101
 

Is there a main disconnection somewhere behind the dash for the door's wiring harness or do I have to rip the harness out of the door?

Blue88, my 1979 Mustang had plug in connectors up under the dash board for my door wires, although my doors only had power door locks. There were no power windows, or door speakers in the '79's. I hope this helped ya.

Hiss
 

This is from an '89 with PW/PL/speaker. I just took a quick peek behind the dash last night. I'll root around back there tonight.

Blue, now that I've had a little more time to think about it, the wires were up under the dash, and they came down behind the kick panels. Behind the kick panels is where the plug in connectors were. I hope you find yours. Good Luck!

Found it.
 

That was strange - I had to cut away a section of black plastic, but I did get to the connectors. There were three in all. The wire also had 6" of slack for some reason. Thanks for the help.