Here's the way it's supposed to be wired. This diagram includes the internal wiring of the regulator, but it also shows the relationship of the ammeter to the regulator and the battery.

[img]http://www.hunt101.com/data/500/D-R_Regulator_001.jpg[/img]

The terminal at the back of the ammeter opposite the one going to the battery is supposed to be the junction block for wiring to the light switch, the ignition switch, and the power to a fuse block, if the truck has accessories such as a radio or heater. The wire from the ammeter to the battery should have NO OTHER CIRCUITS attached to it, because any draw from that side will not be reflected by deflection of the ammeter needle.

I'll look around and see if I've got a more complete wiring diagram that applies to your truck, but the one shown above will get you started.
Jerry

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