Greetings. I'm swapping to a 350 sbc and the alternator that was on the engine has only 1 brown wire (excluding the + connection on the back). I'm assuming the brown wire is the excite wire. I had a 3.1l v6 and I'm trying to figure out with wires I'm going to need to keep from the old connector. There are 2 wires in the connector, one larger red one which seems to be +12 hot and a smaller black wire. I've attached an image to show these. Which one do I need to keep and attach to the new alternator? What are these wires for? Any information would be helpful. Thanks.

Back of v6 alternator connector