Here's a diagram from a Delco service bulletin from the early 1950's. It's common to virtually all DC generator systems back then that used an ammeter. The circuit from the battery to the ammeter will be the same one that runs to the starter switch. Connect a #8 or larger wire from the battery cable connection at the starter and run it to one side of the ammeter. Make ALL other connections such as headlight switch, ignition switch, regulator BAT terminal, etc. to the other ammeter connection. If the meter reads "discharge" with the engine running and the generator producing current, reverse the ammeter connections.
http://www.hunt101.com/data/500/D-R_Regulator_001.jpgJerry
