Hum/drone above 55 mph...Stops when I take my foot off the gas...

When I am pressing the gas and hit 55 mph and above, I hear this low hum/drone, but it stops when I take my foot off the gas. I can hear it consistently above this especially at 70-75 mph. The issue started about 2 weeks ago.

I found a similar thread here: https://www.yotatech.com/forums/f2/...hour-stops-when-i-take-my-foot-off-gas-96392/

Might be the rear differential. This guys sounds way worse than mine, but same issue/description.
https://www.youtube.com/watch?v=KwoMUejhs_Q

My shop said the drive shaft and everything else checks out fine. I don't know what everything else means, so I asked if the ujoints and pinions were good.

What else can cause this hum/drone?

 

Could it be the wheel bearings or possibly the differential?

 

How many miles on the truck? 2 or 4wd? If you pop the truck in neutral does the noise go away? There are a lot of moving parts, any cel's or abs codes?

 

Following. Same issue, past month. Are you sure it goes away with the gas or is the exhaust covering it up?