1972 Duster 340 M&H wiring harness

I was going to change my engine wiring harness today with an M&H one and I ended up aborting the project as there seemed to be some additional plugs/wires on it. I pulled out the 1972 Duster wiring diagram and figured out what 2 of the wires were, but there is a plug in this harness that I can't figure out. It is the plug that you see on the middle of the photo, it is on the black wire that goes to the brake light warning switch plug, if you look at the bulkhead when mounted on the car it is the top left hand wire (drivers side top). Does anyone know what this connects to or what is what for? Another thing is that this car has A/C so there is one A/C wire that seems to be inside the tape of the part of the harness that goes to the alternator. I am assuming that I will just need to unwrap that side of the harness and take that wire out of there. Does anyone know if the A/C wire that goes to the compressor was taped along with all the other wires that go to the alternator or if it was originally outside of the engine wiring harness sitting by itself? This harness has been butchered a bit and I have no idea how it should be.

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