my buddy just recently bought his dads 2007 (classic body style) 1500 chevy ext cab with the 4.3 vortec. it has 180k miles and its in good shape and runs great. it started making a squealing noise on startup and when revved to 3000 rpm. it has a brand new belt, belt tensioner and idler pulley on it, it was squealing before this was all installed. It sounds like it would be coming from the water pump pulley, i pulled the belt off and spun them all by hand, even the alternator pulley, and none of them made the slightest noise. Any ideas guys? He wants to try and get 400k out of this truck.