I was driving my newly acquired '85 300DT and everything was peachy, then seemingly suddenly I started losing electricity. And fast. Within five minutes (at night) I was out of headlights.

I just bought the car a few days ago. The previous owner apologized because it was a remanufactured Autozone alternator, albeit a new one.

I had alternator tested at Autozone while still in the car. With the car off and his tester on the (dead) battery terminals it got a reading of 12 or so volts, but when we started the car the reading dropped to 3.4 volts. He said this indicated that alternator was not bad. Admittedly, I don't quite understand how that test works, so I'm not sure if the Autozone tech's analysis was correct.

Symptoms/Tests thus far:
--Dash battery light stays on
--Battery takes a charge, car starts fine until battery drops
--Multimeter on battery (12V off, no increase while running, steady decrease w/ headlights on)
--Multimeter from negative terminal to block w/ cable disconnected (12V)
--Connections in grounding block all fine
--Cable connections on starter good.

So I'm not sure where to go from here. Thanks for any input you might have!

Chip