Alternator Extra Wire Help

[BuffDrinkLots]

Hey all,
I’m sure this has been discussed thoroughly, but could not find what I needed.

My situation:
1972 C10, External Regulated Alternator (DL7133)

In pic 1 is the wiring from PO, it has a plug in black and yellow wire, and one wire at the Batt location.

In the others pics, is the new factory wiring harness, it has the plug in white and blue wires, red Batt wire and an extra wire that I think is brown or black that the alternator never had previously. I am assuming it’s a ground? Where does it go? I was just gonna bolt it either to the frame or put it with the batt and put the rubber boot over both. I don’t see anywhere on the alternator that says “ground”. Any help would be awesome! Thank you.

[mr48chev]

Backtrack the other end of the black wire but I am thinking that you are correct and that is a ground wire to the Ground bolt on the alternator.

I haven't had an external regulator alternator on mine for years as I changed mine to 10 SI and now a 22SI that came with the Cad 500.

The top photo shows the external regulator alternator hookup on my 71 per the wiring diagram from www.classiccarwiring.com The second shot is the wiring diagram
Big enough and plenty nice enough to put up on the wall of the garage by the truck. They aren't cheap but when you get it laminated it is a nice piece to have to refer to.

[BuffDrinkLots]

Thank you! Appreciate the help, the diagram helps a lot. I’m gonna ground the wire and see what happens, it’s the only thing that makes any sense.

[basketcase]

That extra black wire and the bracket on the harness mount onto that alternator ground post.

Tom