I looked under my SS/T and noticed it still has the factory 3.92 gear tag on one of the bolts..LOL. And you can see the orginal gasket. My guess, the fluid has never been changed in the 100k miles it's been driven.

I'm going to change this week, I already picked up the Mopar additive for LSD but what weight and fluid do you guys recommend? Thanks in Advance

 

I would stick with what is in the owners manaual and not random information off the internet. Just my opinion.

 

80w90 and make sure the whole bottle of additive makes it in there

 

Thanks for the advice, but I bought the truck used and it doesn't have the owners manual. Plus I've never owned a Dodge truck so I figured this would be a good place to get advice.

 

My manual says "the rear axles contain SAE 75w-90 type GL-5 gear lubricant, except Dana models 50, 70, and 80 which contain SAE 90."
Also from the manual, "Multipurpose gear oils meeting specification API GL-5 are recommended for all axles."

Hope this helps.

 

i recommend the walmart brand 75/80?w-90 or 75w-150. comes in a gallon jug at a reasonable price. was $12 last year.

as said be sure and add the 8 oz bottle of LSD friction modifier

 

If you do a lot of heavy pulling maybe the 75w-150, otherwise the 75w-90 is good, Use the lsd fric modifier with either .

 

75 140 if you haul or tow , if you dont 80-90 works well most important thing is to lsd additive if you have lsd and the fact your changing fluid should change about every 30 k as prevenitaive