Is there a difference between 71-73 wiring harness?

Looking for help/insight on wiring 71 73 wiring harness.

I have 2 complete headlight to taillight body harnesses, one from 1971 and the other from 1973. Looking to sell one and keep the other for back up but don't want to mix these up if one year is specific.

Want to know are all 71-73 harness identical and have the same connectors? Mainly concerned with under Dash harness.

I can tell you the under dash wiring is not the same 71 to 73 and I assume the same is true for the other harnesses

Nor is the headlight harness the same.

I have a Mach 1, and the Sport Lamps in the '71-'72 harnesses are on separate circuits from the park/signal lights. The '73s all have park/signal lights in the same place - there are no separate Sport Lamps.

I had purchased a complete used harness from a friend a long time ago just assuming mine was bad, and discovered it was from a later and/or non Mach 1 car - there were no plugs for my Sport Lamps. The dashboard side of it was different as well. So, I troubleshot my original harness and it checked out fine after all.

Midlife would have a lot more detailed information since he restores them, but that's one of the main differences I'm aware of.

Mach 1 and standard are different headlight harness as well?

I would think so, considering Mach 1s have their own VIN codes (Fastback code: 02, Mach 1 code: 05).

I could be wrong, though - it might just be a year model thing.

All 71 through 73 underdash harnesses and headlight harnesses are different for each year, and Mach 1 headlight harnesses are different for 71/72 than standard headlight harnesses. I believe the 71 and 72 tail-light harnesses are interchangeable.

The 73 underdash harnesses differ significantly from the earlier years with changes in the ignition switch connector. It's best to stick to one year or another for wiring. The 71 and 72 sets can be interchanged relatively easily.

Right on cue. ::thumb::

Thanks for all the helpful information. I see folks on eBay list 71-73 for every part but I wanted to know for knowledge. Thanks again.

Another thing that is different is the connector on the tilt steering column, 73 is different I think part of ignition switch changes. The power windows are also different on 73.

I have a 72 tilt column coming out of parts car soon if interested.

David