OK this is driving me nuts. I just got another new alternator, same as pictured before.
I put the first one on as I said right after Romp 2011. Being a Series wiring harness I have two brown wires coming off the main lug of starter solenoid and one whiteish yellow coming from dash. I hooked both browns to the B+ lug on alternator and whiteish wire to tab marked W. It seemed to work although I never tested actual output voltage. I ran it this way for almost two years and never had an issue. Until recently and had alternator tested and was told it was no good.
I just put the new same style on hooked it up the same way and still only getting 12.2V which tells me that it is not sensing current therefore not exciting the field. Common sense would tell me 3 wires and three terminals hook it up that way, but want to be sure before I kill another $300.