2004 GMC Sierra 2500HD grinding while coasting
 

Driving at 65mph on highway after cresting a hill backing off on the throttle the truck makes a high pitch grinding noise. Pressing on the gas pedal causes the noise to stop. After this the check engine light would flash at speeds over 65 mph. The light did stay on. Codes set were U1301, U1070, B2725, C0306, and C0327. The truck runs good. The noise sounds like a piece of sheet metal rubbing on the fly wheel teeth. Almost like something trying to engage but can't. I've seen at least a dozen similar post on other forums but never has anyone replied with the fix.