are you using a regular bolt or does the bolt have "grip teeth" across the bottom of the head where it sits against the bracket?

 

pretty sure its just a regular bolt

 

I've always useda regular bolt and never had a loosening problem. I wonder if you're still not tightening the bolts enough? Try using a star washer or a lock washer. Those will dig into the bracket better.
Or, if you want to get some treats for your engine, a set-up like this is trick, and your alternator ain't gonna budge: Alternator Bracket

 

well i tighten it pretty tight..ok i might get one of those and try it..mise well lol..oh that would be a nice addition lol..so you think that would hold my alternator pretty tight?

 

The top bracket acts as a turn-buckle. Loosen the two lock nuts, and crank the center portion of the bracket till the belt is tight, then tighten the lock nuts. Unlike the slide bracket you're now using, this can't loosen back up on it's own.

 

ok that sounds sweet! i might get that since the squeaking is driving me crazy..i mean you dont wanna hear a squeak, you wanna hear the engine roar! lol thanks camaro