I installed a new alternator, new battery, and new belts last night. Tension feels right (about 1/2" flex). The belts don't squeal or squeek, but when I put my car in either drive or reverse, when I first hit the gas pedal I hear a light "clunk, clunk, clunk" ... as if the belts are catching/rubbing.

Any ideas?

 

When I replaced my alternator I had used the new retainer for the upper mounting bolt which caused the alternator to vibrator wildly. After going in and completely removng the alternator and replacing the original retainer from the old alternator it worked perfectly: