Long story short -- 164K on the clock of a '04 F150 FX4 SuperCrew with 5.4

A while ago it was shuddering bad so I picked up a tube of Ford Spec friction modifier and dumped it in. Stopped shuddering within a week. This was about a year and a half ago. About 6 or 8 months ago I ripped apart the rear brakes to replace and noticed huge amounts of goop on the inside of the 'hat drum' on the disc brakes. Sprayed it all down with brake cleaner, made it all shiney and whatnots taking care to not hit any plastic or rubber parts.

I just got back from a trip to PA from MI, (500 miles one way), and I'm finding a rather large lack of power, so I crawled underneath it and smelled gear lube from all over the rear diff. Looks like its leaking from both sides of the axle tubes and the pinion gears, so I dumped some new fluid in to get it home. Let me tell you, the power was back. So at this point I'm pretty sure I need the entire axle serviced, bearings, clutch packs, all seals etc. I know diddly squat about the rear axle and gears so i'm thinking of getting it done profesionally. Any one have an approximate cost on this?

Thanks.

 

Ermm -- no help at all?

 

Call a couple shops for estimates?