I have a rhythmic hum/growling noise and can feel a slight vibration in the drivers side floorboard. This only happens at speeds above 60 mph. This started after both cv axles were replaced. One shop said wheel bearing going bad but I'm not convinced. 2006 4wd SR5 160k miles.

 

Do a search on the front differential needle bearing/bushing replacement. East Coast Gear Supply makes the bushing.

That may be the culprit. Mine started when I installed a spacer lift. I noticed it when I finished the front but hadn't yet done the rear.

If your U-joints are all ok and neither of your front hubs are hotter than the other after driving for a while, I'd give this some serious consideration.