what fluid?
 

Have a LSD rear diff out of the n/a model that came with them, has the 4.3 R&P (GTUs?). Its a clutch type LSD, correct?

Question is, what fluid is recommended for this diff? Getting ready to install and gonna put fresh fluid in beforehand.

What fluid and how many qts?

thnx in advance

clutch type, correct. book calls for 90 weight. i use royal purple.

I use 75w90 redline with the friction modifier (I think its called 75w90NS)

you need to make sure it as additives for LSD. So look on the bottle to ensure its says "safe for Limited Slip" or something along those lines.