I've got a 1953 2-ton that was converted to 12V by the previous owner. He also put in a new wiring harness. The alternator isn't charging now and I fugured to just replace the 1-wire unit he had in there with a another. Then I noticed the plug that appears to be for a three wire unit zip tied off to the side. See picture below.
One wire on the plug disappears into the harness. The other just has an eyelet on the end of a short wire. I believe that eyelet goes to the battery wire stud, but not sure. What should I do? Stick with 1-wire or use the plug on a 3-wire. If I use the plug, does that eyelet go to the charging stud on the alternator?