Just an FYI....was chasing a buzzing/rattle at about 2000rpms for the past 3 weeks. Was thinking anything from loosening valve lash to some sort of shield vibrating. I was under the hood cleaning and checking things and I heard the strange noise coming from the alternator as I would rev the motor. I thought it was alternator bearing related but it was actually the 3 screws that hold the halves together that were loose!
All tightened up and rattle noise gone! love figuring out a mystery !