My Tahoe has developed a rubbing/low grinding noise that seems to be coming from the rear axle. When I accelerate I can not hear the noise, but when I let off of the gas and the vehicle is coasting you can hear it very clearly. I took it in to a local shop and they checked all the wheel bearings and they said they were fine. Any help would be appreciated.

 

I suspect the rear driveshaft / u-joints.

When accelerating/decelerating you are changing the angle of the driveshaft by a few degrees as the axle twists on the springs. It may be enough to notice in the shaft if it's not in good shape.