I was wondering what the normal voltage reading should be for an 88 GT. My voltage meter consistantly reads about 15-16 volts (almost in the red zone)while the engine is running. Also the alterator seems to making a howling noise. The battery seems to be charging ok. Should I be concerned about the alternator giving up the ghost soon?

I had an overcharging problem that was fixed with the help of a few people on this forum. I don't know about the alternator noise, but my guage just reads a little high - about the same as yours. If you spin the engine fast does the volt warning light come on? Mine does. If you measure the Alt. output it might read normal - then your guage is just off. If the Alt. is truely overcharging its probably the regulator. I'd visite the ogres cave, or hope ogre see's this. He seems to know a lot about it.

True high voltage will set an ECM code. Check the actual voltage with a Digital Volt Meter; the gage isn't exactly laboratory quality. I think if your voltage were truly that high, you'd boil yo' battery!