I changed my own diff oils on a recently purchased jk it was second hand and well the oil in the back was pitch black and very glittery, how can I check for damage to the LSD or clutch pack? Any way I can do so by moving the wheels or something? Thanks

 

What you are probably seeing is debris from the clutches. Clutches wear out over time, especially if your wheel your rig.

Jack up one side of the rear and see if you can spin the tire. If it spins freely your clutches are bad. The factory Trac Loc units are marginal new so this issue is very common. Clutch design LSD units are a bad choice for any rig that might ever have a single tire free spin (like when you lift a tire). Clutch wear during this condition is rapid. A helical driven LSD like a Truetrac is a better choice. It doesn't wear out.

 

OK, so how long should a factory LSD last?
How is it serviced?

 

What he^^ said. To me, it's not really worth the effort. If I wanted to make sure I had a good LSD I'd add a Truetrac.

 

I agree with Dynatrac, the debris you're seeing is probably from your clutches which are more than likely worn. The factory Trash-Loc isn't very good and none of them last very long, mine burned out in under 40 000 km's and I can say with complete certainty that it didnt see much use and definitley no off road use. Truetrac is definitley the way to go when it comes to a LSD.