Humming noise that won't go away
 

My 2007 4.6 Supercrew 2wd has 124,000 miles and about a month ago I had the rear end rebuilt due to a humming/whining noise. After I got the truck back, the noise came back so I took it back to the guy and he changed out the fluid from synthetic to conventional because he said that would make a difference. So he just changed out the fluid on Monday and checked everything out in the rear end and the noise is definitely better but there's still a humming/whining noise from 40-48mph. Do I still have something funny with my rear end or could it be something different?

u joints or carrier bearing possibly

What tires are you running and how long have they been on your truck? The only noises I hear are my tires (until I get that damn exhaust installed). In my experience, when my u-joints go bad, I get more than just a hum or whine. As for carrier bearing, I never had one go on me so not sure what the symptoms would be.

Good luck.

Tires are just the Goodyear Wrangler highway tires that are about two years old and probably have 50,000 miles on them. I've had good luck with them but can't wait till they wear out so I can get some more aggressive AT tire because I've needed that a few times since I've had the highway tires on.