Change 12V Positive Ground to Negative ground

[rotorwrench]

If it is still a generator, which a voltage regulator seems to confirm, the terminal on the side of the unit that is visible should be the field wire to the voltage regulator field terminal. The terminal on the rear should be the armature or generator output wire that connects to the voltage regulator armature terminal. The other wire connected to the G terminal on original Ford generators was a ground wire to connect to a ground terminal on the voltage regulator to insure grounding of the control with the generator. If the generator is grounded, the voltage regulator housing is grounded, and all of the engine, frame, & body are grounded well to each other then the generator ground would come from the mounting of the generator to the engine. The early voltage regulators were mounted on rubber cushions to limit vibration so they needed to be grounded.

It's not difficult to replace components in a 6-volt generator to make it a 12-volt unit so that is likely what was done there. The voltage regulator would be a 12-volt unit and the part number should confirm that.

[Ramblin Reck]

The voltage regulator is definitely a 12 volt regulator. Confirmed