1979 4wd Pickup - Alternator Wiring Help

[Zero]

Vehicle info: 1979 pickup, 4wd, 20r, California emissions, originally A/C-equipped.
I'm pulling my factory 40-amp alternator and blown external regulator for a 105-amp CS130.

I've got all the old parts out, but can't identify a wire using my repair manuals (not FSM, only parts store books).
There is a yellow wire coming from the firewall that connects to the condensor(?) shown in the photo, which leaves as a black wire and runs to the alt/reg plug disaster, where it becomes a ground mounted to the inner fenderwell.

I'd like to know where this wire goes without unraveling the entire wiring harness, and whether or not I need it anymore.

Thanks

 

[Gurr]

Are you sure it's yellow and not a faded white?

 

[welder7018]

dude or dudet junk it and get a chevy one wire and trail gear bracket from summit 100 amp I run dual with one disconnected hooks right to battery bypass regulator

 

[Toast]

IIRC, the yellow wire goes up to your cluster to trigger your charge light, a white wire should be your charge wire going to bat. But it's interesting you say you have a wire going to your condenser. That yellow wire might be go to your A/C amplifier and be tied into your alt some how. I've never tinkered with a truck that old so I'm just going off what I've seen on newer stuff

 

[Toast]

Just realized this thread is ancient.... Whoops