Quote:

Mancini lists the round back as the same from 64-74 when there are actually two styles a single wire (69 & earlier)that uses a pulsed 12v signal to control the output & a two wire (70 & later) that uses a 12v input then a pulsed ground...



If you look up the PowerMasters alternator on Summits web site you can down load the instructions and this is what they say:

"Note that the Powermaster alternator is a double field unit that will work with both double field
and single field type external regulators. If your vehicle has two small field wires, they should
be connected to the FLD terminals on the back of the alternator. These wires are interchangeable, so either wire can be connected
to either FLD terminal. If your vehicle has one small field wire, connect it to either FLD terminal on the alternator. Then, using
a short 16 AWG or larger jumper wire, ground the remaining FLD terminal. Some models have a ground stud on the back
alternator case; this or any other bare metal grounding point will be sufficient."