Squeak / Chirp in Rear Axle Pinion (Differential)

[OxFORD]

Some background ... I have a 2006 Ford F-250 Super Crew Lariat FX4 6.0L PSD. I took the truck into a shop and had a bad set of pinion bearings replaced. The shop did not get the preload right (too loose), and I had a decel noise in the rear end. The preload was tightened, and the noise went away.

After about a week (and after a towing trip), a new noise showed up. This time, it's a squeak / chirping sound. At first, I swore it was the brakes; however, after jacking the rear axle up and running the truck in drive, the sound was pinpointed at the rear axle pinion area.

The noise only occurs on decel after the pumpkin has warmed. I can let off the pedal and the squeak / chirping sound will start at a frequency thats relavent to the drive speed.

I suspected the drive shaft carrier bearing, but it was quiet. I also suspected the u-joints (a typical source of squeaks), but I replaced all of my u-joints with Spicer's (5-801x's) less than 10k miles ago.

Has anyone else had an experience with this sort of noise out of a 10.5" Sterling (or any other diff)? Should I replace the rear joint "again" or tighten the preload just a tad?

[OxFORD]

Originally Posted by The White horseman

Was going to say unjointed but you covered that,

Sounds like you may have to open that back up, pinion bearings may have been damaged as result of the incorrect set up,

What I'm thinking as well; reckon it'd be worth replacing that rear Spicer (nearest pumpkin) just to rule that out? I know the noise is from that area kind of hard to pinpoint if its the joint or pinion (althought I suspect the pinion).