Mschramm

I just replaced both wheel hubs on my 07 F150. First ride I noticed a slight grinding/buzzing noise only on the front passenger side and only when I was going slow and accelerating in 2WD...if I let off the gas it would stop. As soon as I would put it in 4WD the noise would go away. Also, if I put it back in 2WD after engaging 4WD while still driving it wouldn't make the buzzing noise.

firejimcf

Sounds like your IWE ( integrated wheel end) is hitting on edge of inside gear ring when it is supposed to be pulled off by vacuum. Easiest way to check is jack front up with engine running (preferably on lift). With engine running there should be vacuum pulling the gear sleeve in the IWE back off the inside gear end. Actuator, since it is vacuum that releases engagement, in normal position with engine off is engaged on hub.
There is good write up at http://www.f150online.com/forums/art...replacing.html
in the IWE's: Removal & Replacing F150forum
My left side separated and I had to replace it because it was rattling around when not in 4X4.
My experience: raised truck on hoist and checked vacuum at both actuators and had 22 inches each side. With hoses back on actuators checked to see if axles were locked, right was free and left was locked. That showed me there was a problem on left side.

Lower truck to shut engine off. Pulled apart found problem and back together 1 hour 45 minutes later following the Ford Manual to a T. With proper tools this is easy fix. Attached pictures show what I found at http://www.jimboileau.com/fordforum/