I just picked up a used 2004 F150 5.4 4x4 supercrew. I just noticed that when I am accelerating I get a whine from somewhere I am thinking the drivetrain. If I shift to 4hi I do not hear the whining while accelerating at least not consistantly and nowhere near as loud, Just in 2h. I don't know if this is something I should be lubricating or not. Vehicle has about 40,000 on and appears pristine. Any assistance would be greatly appreciated.

As of 12-08-07. This is apparently the rear end pinion bearing. I am going to have it pulled this week and checked. Any other pointers on bearings. Whats the best or worst overhaul kit? This is a 9.75 rear with 3.73 gears. Primarliy a daily driver but occassionaly towing a boat and driving in the dirt. Lots of threads around this kind of problem apparently even a ford TSB if you are under warranty.

Turns out to be a gear. My drive train guy tried two sets of ford oem gears and was unable to get this set up quiet. He has an aftermarket set in now he wants to try, says its 90% quieter than it was. Going to drive it now. I can take it back in and they will try again as soon as he gets another set of ford gears. One suggestions was that it was the axle housing that was causing a problem. In for a G at this point.

Anyone heard of axle housing problems from ford.