Used to have one wire alternators made by local rebuilder and sell them in our auto parts store for many applications including custom hot rods. We even put one in a 1967 Jeep P/U that we put a 427 Chevy into in 1980. No issues with alternator warning lights, at least back then. These were GM alternators. Common rebuilt part # then was the 7127's. In these type of GM alternators they have an integral regulator that is on the side and rear of the alternator. A slot where the regulator sets inside with two male spades. The two male spades in this regulator that would normally be where the plug on the wireing harness would plug into it. On the one wire set up the regulator will be visible from the same location, recessed inside, but will have no male spades. Only location to attach wire will be on back of alternator. I memory serves me correctly when engine RPM's dropped below 500 RPM or close to it, alt. would not charge. Usually hooked the one wire directly to battery.