Rear diff fluid Truetrac ?

I'm installing my gears and truetrac next weekend and need to know what fluid, how much and also if I need the bottle of gm additive?
Thanx in advance!

3 quarts of Mobile 1 gear oil, synthetic, no additive needed, Tru trac has gears in it not clutches...

+1 on the no additive...no clutches in the tru trac = no need for limited slip additive

.....no add I'm in on but might also think about the $27 per quart GM synth too....

I thought with the truetrac you're not supposed to use synthetic, but then again that's why I asked. Thanx guyz!
Also is there a certain weight oil I'm supposed to use or just any mobile 1 synthetic gear will work?

GasGuzzler I wish I could afford that but I already had to borrow money from my Dad for the truetrac.

From what i've read on PT.net (and on this forum too... i think) you are not supposed to use synthetic.

Check out these posts, the last one is prob the best answer to your question:

Built rearend questions.. - PerformanceTrucks.net Forums

Guys Running Detroit Tru Trac Come In.. - PerformanceTrucks.net Forums

Tru-Trac not locking - PerformanceTrucks.net Forums

I called Detroit today and he said "DO NOT USE SYNTHETIC!!! It will cause the gears to slip."

i run royal purple....lol... oh well