What year is your truck?
The axle joint might be bad. Does it make the noise along with wheel speed or make the noise only when turning? Torque on the wheel bearing could be a factor too.
need more info
A 2005 , and it makes that sound with the wheel speed, as long as it is in motion, but when in regular driving outta the 4x4 it doesn't make that sound at all, if that makes sense,