It might also be the voltage regulator going out or something else. I went through the same thing with my externally regulated rebuilt 1970's style chevy alternator the FHP installed. I had the thing rebuilt about 4 or 5 times (every 8K) before finally buying a rebuilt 3G. I've never had a problem since (about 30K). The only work you'll have to do is to grind down the bracket a little bit. It should only take you about 30 minutes to do the job since by now you're an alternator swapper expert
.