RE: Diff fluid for Jato
found the manual online-
Sealed Limited Slip Differential
The sealed limited slip gear differential can be precisely tuned with lighter or heavier lube for maximizing rear traction and cornering performance. Superior silicone-seals are used for reliable sealing. Unlike a ball differential, Jato’s sealed-gear differential never slips or wanders out of adjustment, and it is virtually maintenance-free. It’s definitely the best solution for the demands of a high-performance truck like Jato. You get all the benefits of an adjustable limited slip differential without all the maintenance hassle of a ball diff. Jato’s transmission design provides easy access to the differential. Just remove four screws and the rear cover and there it is. Trackside tuning is fast and easy.
Sealed, limited-slip gear differential is fully tunable with standard silicone shock oils. Ball differentials simply can’t compete for tunability, efficiency and reliability.