New alternator noisey

I put in a new reman alternator on my Jeep from O-reily's and it makes a considerable amount of noise. It doesn't sound like necessarily a bad noise like grinding or something else. Its just a running noise. The original didn't make any noticeable noise and my cousin's all have XJs, a 95, 99, and a 2000 and none of their alternators make any noticeable noise like this one. Could this be a problem with the alternator? Or is it just a noisey alternator? I have given it time to "break in" so it isn't like I put it in yesterday and I am complaining about it today.

belt too tight?

I tried loosening the belt and it is still the same and I tried tightening it some more also with no change.

Take it back and exchange it.