Hey all - I am having the same issue. This humming occurred after the suspension lift. Front diff drop has been done and OEM shafts.
Alignment does change a bit, even with diff drop.
Swapping on a set of soft tires, of known sound. May help isolate. It's a sure way to eliminate, tire sound as culprit.
Started with replacing wheel bearings, had national showed some wear, not very loose compared to most I see.
Should not have any play, whatsoever!
Small aftermarket cv’s replaced with Cardone HD. Noise changed but still there. That’s the only point it really changed. Vibration went away just a hum 50-65.
What was condition of needle bearings. Best clue is where the needle bearings ride on outer axle of FDS (AKA: cv)
This FDS axle had less than 2K miles on it. Needle bearing scored axle, unevenly. Notice the different and narrow bands of color variation. Replacing needle bearing illmated, the unusual rotational sounds.
GoPro attached to FL, help me islote sound.
Lowered loft and seemed to reduce noise but still there.
This would reduce angle on FDS. If hub flange snap ring gap to wide, it may result in slight change where needle bearing, knuckle & FDS outer seal butt/rub and contact with brass bushing.
Replaced cv with oem. No change,
dropped front drive shaft, no change,
removed drive flanges, no change,
did an x tire rotation , no change front flanges and shaft installed removed rear drive shaft no change.
Changed tires 30-35psi. Maybe slight change but splitting hairs.
I'd then, for sure swap on some quit tires.
Have shifted transmission and transfercase to N at 60 ish no change
Looked at fluids in both diffs and transfer case, diffs show wear but no smoking gun and isolated with drive shaft removal.
May want to try, after tire swap and inspecting FDS axle. Switching gear lubes one gear box at a time. Maybe even add some gear lube additive.
Next steps are alignment check and tire/wheel change to assess noise change. Any help or thoughts would be appreciated.
Very good next step. I keep a set of soft tires on wheels, that ride very quiet. They work great as a tool, to rule out tires.