I have a 1955 Willys Pickup mounted on a 1985–86 Toyota pickup chassis, powered by a 22RE engine and drivetrain. It’s truly a “Frankenstein” build.

I recently installed a remanufactured WILSON alternator (Model 90-29-5152), but I’ve run into an issue: the alternator has three terminals/pins, while my truck only has a single wire for connection. I’ve already connected the main output to the battery, but I’m unsure which of the three pins the single wire should connect to.
I would like to know what pin to connect my single wire to so the alternator will charge the battery.

I’ve attached some photos to help illustrate what I’m dealing with.