02 Tahoe

I thought the humming was from the rear diff, but everything looked fine when I changed the gear oil a few months ago. I'm not ruling it out since the humming stops when letting off the gas which definitely sounds like diff.

I've also noticed on cold days that it feels like something is bogging down on acceleration and deceleration. It usually gets better after a few miles.

 

bearings growl at highway speed and the noise will change tone when the vehicle is swayed left and right...this loads and unloads the bearing.

diff can howl from the crown and pinion. pinion bearings growl when loaded...ie acceleration and r quiet under coast.