Un-converting a Powermaster swap

Does it still have the factory bulkhead connector? If it does your best bet is probably just to buy a new engine harness and not worry about sorting out all the PO’s shenanigans.

Yes, though the ammeter is long gone.

There’s nothing wrong with 1 wire set ups. It does the same thing as the external voltage regulator, the voltage regulator is just internal. And power master alternators are decent too, I have a standard external voltage regulator version on my Challenger that was there for most of the 70k miles on that car. And I had a standard one on my Duster up until I installed a much improved American Autowire harness, which required a 1 wire alternator. So now it runs a 1-wire power master.

Mine was awful. Quality is dismal (mine is totally dead after 5 years and <10K miles-local shop that specializes in hot rods will no longer install Powermaster due to quality problems), voltage regulation is awful. Temperature compensation is nil. Also, as I have found, the only fix shrot of rewiring seems to be dropping a few hundred dollars on ANOTHER expensive, poor-quality Powermaster and hoping it will last more than 10,000 miles.