Here's what my notes say for using the two pin voltage regulator with the Magnum alternator-
Blue wire at Regulator- Key Power 12v
Green at Regulator- One of the Alternator Field Wires
Other Field Wire- Ground
On the factory Magnum harness the Green/Black field wire at the alternator is key power and the other wire is grounded through the ECU.
I lied to you. Here's the correct way to have it hooked up:
Blue wire at the regulator is key power, that same blue key power wire also gets run to one field of the alternator.
Green wire from the regulator goes to the other field wire.
Sorry about that.
-Jon