I know this site is for camaros but you guys have helped me out in the past. I have a 2003 Chevrolet C2500HD pick up with a 6.0L. I have had the truck since new and it has always had this whining noise. Noise is heard from 1900-3000 rpm. Loudest at 2500. Is worst when engine and trans are hot. It sounds like a idler pully or altenator. Dealer has looked at it twice and has replaced the alt. , was slightly quieter for a day but after that could not tell a difference. Noise is also most noticable in drive, not so loud in park, but can still be heard. Under the hood you can here some whine from the alt. idler area at those rpms but nothing excessive. Could it still be the alt and it has a lot of load on it in drive rather than idle? The alt the dealer put on was a re-man not a brand new. I brought the truck to the dealer today with my trailer to make sure every thing was good and hot and I could not duplicate the noise. and as soon as i got 10 miles from the dealer it began to whine again(really pi**ed me off). Noise is driving me out of my mind. Hopefully one of you knowledgable gentlemen have had this problem with one of yours and could steer me in the right direction. Thanks Nick

I had a 94 with a 5.7 and it also whined, finally the dealer replaced the AC compressor ( because they had replaced everything else ALT, Idler Pulley , and PS pump. ) that fixed it.