Pete,

You can drive the car<?> I had an 86 xt6 and the alt went out on me when i was doing a long distace drive. Anyway after the alt quit i started running on the batt (not to my knowledge), once the batt didn't have enough juce the car wouldn't accel and all that i could do was coast to the side of the highway. I was able to jump/charg the batt for about 20 min and i was able to drive the car to the closest off ramp (less than 10min, 5 miles or so) and park it until the tow came. So if you can still drive the car with out fully charging the batt it sounds like the alt is still working. Try juming the car then removing the neg batt terminal, if the car still runns then it is not the alt. As mentioned before it could just be the terminals, dirty etc., just causing the batt not to charge. Since the batt is new it could have held a good charge this whole time and you may not have been charging the new batt the entire time you have had it.

Good Luck. Hope all is well.

--Adam