alternator not charging

So I have a 94 mustang gt with a swapped 93 cobra motor. When I bought the car in the spring, it had some sort of upgraded alternator used for sound systems (there’s no radio or upgraded speakers). That alternator went bad so I went to autozone and picked up a new one. Threw it on the car and...

I have a 1996 Mustang GT, 4.6L of course. It is bone stock, aside from interior. I have had issues with the car burning up alternators in just a couple of days at the most. this is the 3rd alternator in one month. I cannot figure out what is causing it, Ive checked fusible links and fuses...

So...I drove my 90 GT the other evening as I often do. Didn't notice anything unusual while driving it but then again, I only drove it a half mile. Brought it home and parked in the garage. Next morning I went to use it and the battery was almost dead. Wouldn't start. Every once in a while...