I have used a 1 wire, no external regulator, no idiot light, and I used the stock 1954 Ammeter (12V system). However, my alternator is probably 45amps.
I did not need/want any more wires.
It was installed around 1997 and is still working fine. It "excites" at around 800 RPM. When you start the truck, you normally go above 800 RPM. Once it is "excited" it charges at all RPM.
