If you have a true-one wire alternator than you cannot use the DA Plug. The advantage of using a 2-wire alternator and a DA Plug is that you will have a charging output at engine idle and low rpms. The yellow wire of the DA Plug is called the "exciter" wire and send a little bit of battery current to the alternator when you turn on the ignition switch so the alternator will begin charging as soon as the engine is started...regardless of the idle speed of the engine. A one-wire alternator typically does not have much of an output below 1200 rpms engine speed and your old truck does not idle at the 1200 rpms that a one-wire alternator was designed for. That is why a 2-wire alternator works better in older vehicle applications.When one-wire alternators were introduced they were originally for racing applications that ran only ignition and electric fuel pumps etc. By that time most everything was V8 powered and had idle speed of around 1200 rpms so that is the speed one-wire alternators were designed to begin charging. A one-wore alternator will usually not begin charging until you exceed the 1200 rpms cut-in speed of the alternator. Sometimes they will "drop out" or quit charging if the rpms get to slow like at a stoplight at night. You will notice it acting like an old generator charging system. Not a big deal and once the rpms come up the alternator will begin charging again. You just need to understand what is going on.....thanks Randy

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