I am not sure this is where I would post this kind of question....but here goes I have a 83 with the 6.2 my volt gauge will show 14 volts with nothing on . If I turn anything on it will drop to 13 volts even at hiway speeds . I have checked the alternator and I show 14.5 volts at the output post I have checked down at the starter and 14.5 . Followed the wires up to the top of the firewall and 14.5 and and the other side of that connector and get 14.5 ? Guage during this time shows 13 volts . The other day I truned the Air on high and was doing some idling around a parking lot and watched my volts drop so low the Glow plugs kicked in !!!So I know there is low voltage some where ? Please help !!!!!!!