A friend of mine found that exact same piece while doing a lube change on his
Durango and he had to take it in for a rebuild under extended warranty.  I'll
find out exactly what they had to replace and get back to you.

That looks like a Chrysler 9.25" rear end. You have to find where that piece
of metal came from.

This rear uses side adjusters instead of shims, which makes it easy. To
remove the carrier you remove the two 3/8" locks, which will allow you to
loosen the side adjusters (round disk with holes), then unbolt the main
bearing caps and the carrier and ring gear will come out. Also, you will
first need to withdraw the axle shafts. Push in on the axles, then remove
the C-clips inside the spider gears, then pull the axles out.

Tony

when i look at the piece, it looks like one of the side adjuster locks broke
off.,, If so that would throw the ring gear adjustment out of whack.

Tony

YIKES!  You say "unusual" damage, the drive faces of these gears should
be as smooth as mirrors.  Any small nicks or dings will cause
considerable metal-metal contact and overheating, especially at highway
speed.  The hypoid gears make a VERY sliding sort of "contact", and if
there are mars on the surface, that will cause rubbing of the metal.
They will eventually smooth off again, I suppose.  if you do try to
continue using this differential, I would see about getting magnetic
drain plugs for it, or making them if you have to (not very hard).
Then, I would go out for a short drive, drain the diff and refill.
If you want, you could take the oil and run it through a fine filter
and reuse it.  A large filter paper in a funnel left to drain overnight
should get the metal out.  The full diff contents might take several
separate funnels to run through in one day, though, as that stuff is
awfully thick even without foreign matter.

Otherwise, I'd keep draining and refilling it at gradually longer
intervals until you don't see any metal on the magnets anymore.
Of course, you HAVE to find out what bolt that retainer flap was
SUPPOSED to hold in place, and re-do that section.

Oh, hell, I didn't even MENTION bearings.  This kind of crud must be
even harder on the bearings than the gear teeth!  I think the main
tapered roller bearings may SOUND fine right now, but they are going to
fail for sure after this abuse.

Jon

Really hard to say just looking at the pictures but it looks like the drivers
side adjuster keeper is broken off.  The gears don't look bad but the backlash
should be checked and some prussen sp? blue used to verify the contact area.
You're going to need a special tool for setting the torque on the adjusters.
You have to do it with the axles removed.  The tool is simple enough to make.  A
nut welded on one end of 2' of 1/2" all thread and a hexhead pipe bushing welded
on the other end.  The right size hexhead has to be selected to fit into the
adjuster.  You might as well replace the wheel bearings and seals while you have
it apart.  Don't forget to check the backlash every time you change the
adjusters and after you torque every thing down.  Make up a jig to hold the dial
indicator that bolts to the case using one of the cover bolt holes.

beekeep

That same part was in a friend's diff when he did a lube change, I asked him
what the warranty company had to fix on his and he replied:

There's a lead for you, a TSB.