I have a NAPA alternator on my 80. It's the 63 amp output style stock wiring configuration. Sometimes at idle it does not charge (charging system reads about 12.3V). When I give her a good blip on the throttle it starts to charge (around 14V). I was looking at the wiring and there is one red wire that goes to the post on the back of the alternator and splits and goes to the two wire plug on the alternator and the other end goes to the fuse block which then goes directly to the battery. The other wire in the two wire plug is a white wire and is known as the exciter wire. Is this the wire that is messing me up and where does it go to? This is the second alternator which I have gotten (of the 63 amp style) and they both have done this. Is this normal? I'm just worried that I am going to leave it idling sometime with the truck running and lights on and it's going to drain. Any thoughts?