Grinding noise and vibration

[Jkt05_1]

I have a 2012 Chevy Silverado 1500 Z71 with a 6" lift kit and 35's on it. I'm hearing a grinding/vibration noise and feeling vibration in the gas pedal and steering wheel when I let off the gas. It only starts being noticeable when you hit about 40+ mph but it gets even worse at 65-75 mph. I've had the lift kit on for about a year before the problem started.

[arcasey]

Vibration and grinding only happening when you let off the accelerator or is it noticeable at other times? Does the vibration/grinding noise change with vehicle speed (i.e. lessens as the vehicle slows)?

[anumber1]

U joints.

 

The lift adds a lot of angle to the rear driveshaft.

[Jkt05_1]

It happens when I let off the gas or if I'm just resting my foot on it but not pushing it. As soon as I give it gas it goes away instantly. The vibration in the gas pedal isn't as bad as the grinding/vibration noise itself. The faster I go the more noticeable it gets.

[JBrew]

On 1/13/2017 at 2:11 PM, Jkt05_1 said:

It happens when I let off the gas or if I'm just resting my foot on it but not pushing it. As soon as I give it gas it goes away instantly. The vibration in the gas pedal isn't as bad as the grinding/vibration noise itself. The faster I go the more noticeable it gets.

You ever figure this out?