The wiring harness shown in this Ebay ad has a diode built in to prevent engine run-on when the ignition is shut off. The red wire goes to any constant 12 volt source, such as the big terminal at the top of the starter, or the ammeter, etc. It can be connected to the charging output terminal of the alternator, but there's usually a slightly more steady voltage reference a few feet away from the alternator. The white wire is connected to any switched 12V connection, such as the ignition on/off terminal at the dash switch, or the ignition coil (+) terminal. The heavy charging current lead can be attached to the ammeter, the battery cable terminal at the starter, or directly to the battery + cable clamp.
www.ebay.com/itm/191103912421?Jerry
