Well, I just picked my truck up with 10 miles on the clock. About half way home I would hear this metallic buzz/rattle multiple times and at idle. Any one have/had any clearance issues when the metals got hot? I'm thinking this is what is it, drive fine, no warning lights. I got under it (of course everything was blazing hot) and to me it sounds like a metallic clearance issue that came up one everything heated up.