Based on what you're able to tell us, none of us can do any more than muse about likelihoods. It could be the alternator is defective. It also could be the installation is faulty. The VR/brush assembly could have an out-of-box defect, or perhaps the brushes don't make good contact with worn slip rings. I've never heard it mentioned before that Autozone will offer a distinction between alternator and regulator -- and if someone there were diligent enough to try to make that distinction, it would be he or she replaced the regulator and re-tested.

My best attempt at advice is to take your alternator to a rebuilder. Look in the yellow pages (or ask Siri, whatever) for automotive electric shop. The expertise will be there. Also, the likelihood is whatever they do for you will greatly exceed what you'd get in one of those "lifetime" rebuilt alternators in the box from AZ/Advance/O'Reilly's/NAPA etc.
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Art Benstein near Baltimore

"I was worried that my mechanic might try to rip me off, I was relieved when he told me all I needed was turn-signal fluid."