Gear Oil?

[Gr8ride]

Hi,
I have a 2006 Dodge 3500 Cummins 6spd. manual with 4x4.
I would like to know which gear oil to use and how much is needed for the front and rear diffs and for the trans.
I was told that i have to add a friction modifier of some sort to the diffs, is this trure? If so what type?
I also need to know fluid type and capacity for the transfer case.
Thanks in advance,
Gr8ride

 

[condor74]

I use mopar 75-90 sythetic in the front and rear diff. No friction modifier is needed. There are no clutches in these axles even with limited slip.

I am not sure on the transmission...If you climb under your truck and look at the side of the transmission it may have a tag on it specifying what fluid to use. Look near the fill plug area.