Sounds like your wiring harness is bad. Lots of people have rerun the alternator wires and abandoned the old ones in the harness. My alternator has a fat red cable and a small red wire disappearing into the harness. There's also a black wire from the oil pressure sensor that disappears with the two red ones from the alternator. The diagram I have shows the small red 18 gauge wire going from the alternator to the instrument cluster then from the cluster to fuse 13 via a blue/red wire. The fat red cable is shown going from the alternator to the starter, then on to the battery hot side. From the positive battery post it also goes to the ignition switch. Get further advice though. My auto electric skills are not strong at all.

I've tried all the stuff I mentioned in this thread with no luck. My light still glows and gets brighter at higher rpms. I'm at a dead end for what I can figure out. I'm going to follow the advice of a fellow poster who said to take it in and have someone test the alternator in the car under load. My wiring harness is a new-used one from Barton. I doubt if it's shorting out inside, but I suppose it's possible. My problem did start immediately after I installed the new harness, so it's possible the problem is associated with the job in some way. I thought it might have been caused by the fact that I hooked up the fat cable at the alternator without the insulating washer and drew big sparks when I hooked up the negative battery cable, but I was told that this probably did not cause the problem. For now, I'm stumped. I'd sure like to fix it though because it bugs me.

Good luck. Let us know how it works out.
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Thanks everyone for all the information and advice, Doug C. 81 242 Brick Off Blocks, stock, B21F, M46; 86 244, B230, 140k , auto.