Random part floating around in axle housing...?

[Chryco Psycho]

At least there are no parts floating around inside the diff to chew up the gears !
If you are planning to rebuild it again with 3.23 gears shortly I would leave it alone for now .
The Power lok has to be really the best system available , I like the design of the Tru trac in the way it locks just from gear pitch angle so it is unlocked with feedback from the wheel but locked under engine  load , personally with what you have I would not spend a dime to change it out  , when you install the 3.23 gears check the clutches at that time .
You may decide the 3.55s work great with the 8 spd trans anyway  .

[RUNCHARGER]

I just have to say that if you're running 500HP, manual transmission and sticky tires that for the money to regear and rediff your 8 3/4 that you can buy an S60 for similar money and it will be bulletproof. The 8 3/4 will eventually fail in those conditions. The S60 is heavier but it will take thousands of 5000RPM clutch drops with sticky tires, the 8 3/4 won't.

[Chryco Psycho]

 

[7212Mopar]

Truetrac or the SureTrac are Torsen type differentials that lock and unlock at a fixed ratio. No discs to wear or replaced. So great for reliable street performance. Disc types will wear and becomes open eventually if not replaced. However, it allows you to replace and use different disc combo to suit track conditions. So better choice for racing.