Diagnosing rear hum.

Im trying to get a good idea of where to start taking stuff apart, on my dad’s 2007 Liberty.
I have a deep hum coming from the rear somewhere. It only start when on the move, and increases in intensity and depth as I speed up. I couldn’t reall tell if it was on one side or not.

I’m hoping to not rear end bearings, but something simple like U-Joints/CVs.

Id swap the tires front to back and see if it changes first. Hear any clunks when you put it in gear or go from reverse to drive? Or noises when you get back on the gas when coasting slowly?
Plenty of ways to check your u-joints if you wanna see if its them though. If check a few more things before you decide to start taking stuff apart though. Crawl under it in park and see if there's play in the u joints.
Jack up the rear end with the tires on it and see how much play is in the rotation of the tires front to back to check play in your gears.
Last time the rear end fluid was changed? I used to have an annoying hum in the back from a dragging parking brake.

No clunk. The hum is there constantly when moving. It just intensifies in loudness and deep tone when speeding up. I’m putting it up on jack stands today to do some more diagnosing. Thanks for the ideas.

Did you find it?

Did you find the problem? I know its been a while but i just saw this searching for something else. I recently threw a weight on my drive line and it acts similarly to what you discribed. Also wheel balance, driveline angle if its lifted, cv's, wheel bearing, loose dribe line bolt. Thats all I can think of most of what you already said...

I'd start by checking for play at u-joints etc & drop the difff cover & have a peak in there, any crap /particles on the magnet?
You are suppose to change the diff fluid frequently, like every 30k Max.
Refer to your owners manual for fluid/ gear lube specs.
Wheel bearings..check for play on stands.