limited slip differential maintenance?

[BerniniCaCO3]

So the new old wagon I bought last Saturday, has the 3.55 limited slip gears in back, I just learned.
My own daily driver, the same wagon, has 3.08 open gears.

When I did the diff fluid on my 3.08 wagon, it was dark and smelly, but smooth.

When I did the diff fluid just tonight on the limited slip diff on this new wagon, it had the viscosity of elmer's glue, thick and gloppy, and had what looked like clutch material, such as you'd see in the pan of a failing transmission. Quite a lot of "clutch material." It was dark green and grainy. I've heard that when a limited slip diff fails, it acts like an open diff... this still acts like a limited slip. That info might also be for a particular type of limited slip diff.
Does the limited slip differential have clutch material? As evidenced by the condition of the fluid, has that material reached the end of its life? Can it be serviced?
Or, is this in fact normal for these differentials, and just refresh the fluid and go?

Which is in fact what I did. I was advised by a coworker NOT to hose down the gears with brake cleaner, in case the brake cleaner didn't completely evaporate before I closed it up; so I left a certain amount of diff fluid still coating the surface of everything, and poured in fresh 80w-90 synthetic gear oil and a friction modifier we're apparently supposed to use with limited slip differentials.

Is there anything else I should know about keeping this differential in good operating condition?

[mcninetyone]

Yes, a locking rear end does have clutch'es in it, and if they are totally worn out the trac-lok needs to be rebuilt. And besides the regular gear oil they also use that special trac-lok lubricant. I'm sure there are others here with much more knowledge about all this than me though.

[pantera77]

Just because it acts like a limited slip in the air doesn't translate to it actually working on the ground. The junkyard K-code rear end I put in my old 91 Marq worked, and looked fine when I disassembled it, once in the car though, one wheel wonder.

You can buy a rebuild kit for like $75, not that hard to do.

[gadget73]

Its probably got some wear. Only fix is to rebuild the unit. Or leave it alone, refill with fresh fluid and worry about it later if its still somewhat operational. If the clutches totally wear out, it acts like an open diff. It doesn't cause any other damage. There aren't any special procedures with the traction lock, other than using the friction modifier when changing oil. It is useful to mop out the bottom of the pumpkin when draining oil though, just to scoop as much of the clutch pudding out as possible.

[BerniniCaCO3]

OK. So not a sign of anything wrong, just normal wear... though a warning that in time, it will normally wear all the way through on me.
The rebuild kit, I'm not too worried about $75, but how about time to install and precision required? I've heard that setting up a new ring and pinion gear requires some real care and consideration with a micrometer and shims to do it right and is a PITA. Are new clutches much simpler?

There was an oil spill on the floor that I had to drive through, and I did determine that the limited slip still works, haha.
For now, anyway. I don't know what the lifespan is on these clutches; I presume it's like brake pads and its wear life depends on how limited your slipping is [driving style] and that straight lines on a highway won't use them up as quickly.

[sly]

if the bearings are good when you rebuild the diff, there's no real issues with adjustments. Drop it back in and go. The problem will be that pesky S spring. It's quite a bugger to remove and replace.

side note: gear oil with friction modifier STINKS.