03 fx45 uneven whirring sound while driving?

[Bluebeast]

My girlfriend just bought a used 03 fx45 with 60,000 miles on it. it now has 70,000 miles and I noticed it makes an uneven whirring noise noticable from inside the car while driving. could this be an axle that needs to be greased, or the wheel bearings? If so, where are the grease fittings located? thanks in advance.

[themerchant]

wheel bearings are replaceable, but not serviceable (w/ grease). Im sure it very similar to the Gs

[Bluebeast]

Thanks, just getting time to look at this and did some regular service work on this truck, oil change filter/ air filter check etc,everything looked good 6 and a half quarts of oil drained without any adding at 4500 miles.... even looked under at the axles and can see no visible damage, even though I know it goes much further than a visual check. what would any 2003 fx 45 owners look at before taking this to the dealer for diagnosis? I dont really wanna pay three times as much for this fix. should I take the whole axle apart from the differntial to take a look because it makes the noise especially turning right which is the side the differntial is on...or should I dissasemble the whole diff? and if so do I have to take the whole diff apart or is there an easier way to fill it without dissasembling? thanks in advance for any replys!!!