Ive got a 2003 ram 1500 4x4, 5.9l magnum engine with a anti slip diff. What differential gear oil are you guys using? The manual i have specifies:
REAR AXLE:
9 1/4 - Mopart Synthetic Gear Lubricant 75W-140
10 1/2 AA - Mopart Synthetic Gear Lubricant 75W-90
11 1/2 AA - Mopart Synthetic Gear Lubricant 75W-90

Any help with this would be great.

 

Im not quite sure what your asking here, but if its what axle are you running and therefore which oil, you will find the answer in your glove box.
Open your glove box and there is a label stuck to the inside, probably saying Corperate 9.25, with the gear ratio, thus your oil is 75w140.

 

yup, all 1500 non-MegaCabs have the AAM 9.25" rear and require 75w-140. Mopar or any name brand synthetic will be fine and don't forget to add a bottle of friction modifier since you have a LSD...

 

I use the royal purple gear lube, never had a problem with it ever.

 

I now use RP in the front of the truck, change it every 30k. Lucas conventional in the rear, with a bottle of friction modifier, changed every 15k. (Auburn Gear strongly advises against the use of a synthetic with their LSD, so adamant that they will in fact void your warranty! )

RP in both axles on the Grand Cherokee, no friction modifier as the lockers in both axles on an Overland are gear type.
As a matter of fact, not long after I bought it, I noticed a shutter and a chatter when going around turns or backing out the driveway. Was worried the rear and was going. I pulled the pumpkin to have a look, couldn't find anything wrong, and put in RP before sealing in back up. Within 5 miles of putting in the RP the shutter and chatter went bye-bye...

 

Because of clearance specs. Synthetic is a thinner oil by nature compared to Dino oil. It otherwise, "lacks" the body for full protection for their called specs.
Well, that's my guess anyways.