[Beastmaster]

Oil: Shell Rotella Synthetic 5w40 or Shell Rotella T 15w40. Other recommended oils are Chevron Delo 15w40, Lucas High TBN Diesel 15w40 (note the pattern here?), and other API or API compatible diesel 15w40 oil.

Quarts - 8 with filter.

Oil Filter - Delco PF-1218

Geared Hub Oil - Gear Oil. I use Lucas Hub Oil (when I know I'm doing heavy 4 wheeling) or a Synthetic 75w90 Gear Oil (when it's mostly street).

TT4 - Stands for TorqTrac4. Long story short:

Differentials in an H1 utilize a Torsen (Torque Sensing) worm gear based limited slip differential. This type of setup will "lock" the differential axle shaft sides up to a specific bias ratio to maintain traction. Once beyond that bias ratio, it will unlock and allow one axle to spin more or less than the other one

H1's that didn't have ABS have a 4.5:1 bias ratio, where one side will have 100 units of power, and the other side can have up to 450 units of power before the differential will "differentiate".

To fool the Torsen into being locked, you can lightly apply brake and throttle at the same time. This is known as BTM, or Brake Throttle Modulation.

Well, ABS forced AM General and Gleason Zexel (MFG of the Torsen) to lower the bias ratio. The lower bias ratio forces the ABS computer to do BTM for you. It detects wheelspin and then applies brakes to fool the Torsen into moving the side that isn't spinning.

Hardcore off roaders hate it. It works, but most people that really off road their trucks put in a Detroit, Auburn, ARB, or Eaton locker.