Well, the third time might be the charm. The local Ford dealer rebuilt the differential twice on my '01 Screw due to an annoying whine at 40-50mph, once at 12k and once at 34k, but the whine remained. Finally, with 35.8k miles, Ford engineering conceded that there was probably a casting flaw in the housing such that the pinion depth could never be properly set, and authorized the dealer to replace the entire rear axle assembly, guts and all, less the axle shafts and brakes. This seems to have licked the problem (knock on wood with crossed fingers). Must give my compliments to the service advisor for persevering and seeming to work for me instead of against me, as so many seem to do.

SM

 

I may have the same problem with a 1998 F150. A mechanic has just told me that the rear end needs to be rebuilt after he drove the truck for a short distance (maybe 200') and heard the whine.
Can you tell me who to contact that may help me resolve this.

Thanks

 

I'm not sure how to help. I was working through my local Ford dealer since my vehicle was still under warranty at the time. I understand that differential work can be expensive, so I was trying hard to get it done under warranty, and I am glad that the dealership and service advisor were cooperative. In your case, since your vehicle is out of warranty, I'm not sure if you have much choice but to bite the bullet and pay for the repairs, if that is what it really needs. You might try getting a second or even third opinion, especially from a mechanic or repair shop that specializes in differential work.

Sorry, I know that's not much help

SM