I have an 08 sierra with a bb tune and a vette servo. I have a noise coming from under the truck that i cant pinpoint. I feel like its in the drivetrain. it seems to be most noticable when you are in the gas and goes away when your just sitting idle. Truck has a 5.3 60e and 20k on it. The trans fluid is good and clean full as it should be. What else or how to narrow this down.

 

Differental maybe?

 

Anything I should notice

 

differential when the truck is at idle? Put the back of the truck on jack stands and have someone work the gas petal while u look under the truck to pinpoint it

 

will try to do this