Over ten years ago I replaced the Motorola external regulator alternator with a Delco 10 si. It had worked flawlessly until about six months ago. The alternator wasn’t putting out any voltage so I replaced it. The new one was running about 16 volts which I think is too high. At the battery. I was only reading 12.4-12,6 volts. The new alternator then crapped out and I replaced it again. I’m getting the same numbers again with another 10si. When I turn on the headlights, the voltage at the battery drops to 11.6 volts.
I’ve checked the wiring for obvious issues and repaired what looked to be out of order.
I’m about ready to switch the three wire over to a one wire. I did it on my cj5 and it works great.