Gears & Axles - Couple of Stock Diff Questions(WS6)

I have a 2000 WS6. I'm going to change the diff oil soon. Couple of questions

1) How do I know what kind of diff I have? Auburn, Eaton, Torsen(I think those are what they put in them).

2) After the cover has been taken off, is it a good idea to clean the inside of the differential with break cleaner or something similar?

1998 and earlier-Auburn
1999 and later-Torsen

just wipe the bottom out thoroughly,don't take a chance of screwing something up by washing out with a harsh non-lubricant.
clean off the magnet that's on the inside of the cover,don't be alarmed that it looks really 'bad',it's doing its' job by removing from the fluid any iron/steel particles.

So correct me if I'm wrong then, the Torsen diff doesn't use clutches like the True-trac ones? I thought that was one of peoples main points when complaining about these rears?

Torsens take Synthetic Oil correct? And you "can" add the GM additive to keep them quiet?

Also I assume I will need a new gasket? Or it RTV better?

So correct me if I'm wrong then, the Torsen diff doesn't use clutches like the True-trac ones? I thought that was one of peoples main points when complaining about these rears?

Torsens take Synthetic Oil correct? And you "can" add the GM additive to keep them quiet?

Also I assume I will need a new gasket? Or it RTV better?

Yes, both Torsen and Truetrac are all gear.

GM service manual specs synthetic gear lube.

Additive can be added but it won't effect noise/quiet (most synthetic gear lube name-brands already contain LS additive).

New gasket from GM (these are thicker than the Felpro ones).

My vote is rtv, I use blue permetex, never leaks, cheap and available. Not sure about ws6, but auburn was an option on the SS...and you need nonsynthetic and additive for auburns.

What do I use to change the gear fluid in an 02 t/a with the 3:42 set up? I believe it should be synthetic but im not sure. Should I go with GM fluid?

2001/2002 have the torsen differential, for this GM specs synthetic gear lube, use any that you can buy at your parts store (e.g. Mobil-1 75W-90), it is cheaper and better than GM's.