ok, i changed my alt. it had a bad bearing but I still have a slight whine. is the idler pulley bolt a LH thread or RH thread on a 99 GT? I have a used pulley/bolt from a 98GT but it might be from my caddy/northstar. dang, i can't remember which car that pulley came off of. lets see, i think the pulley is pushed "Down" with the wrench towards the firewall to release tension so a right hand thread bolt would come loose if you turned it CCW. i am thinking the bolt is LH thread so turning it CW should loosen it but my mystery pulley has normal RH threads. must be from the caddy.