Generally the bottle will only mention the modifier if it has it included. So if you buy a bottle of synthetic valvoline or Mobil 1 there's no mention of the friction modifier. You need to buy the tube of friction modifier separate at a parts store for $10. You can use that tube 2-3 times IIRC. It could be cheaper to buy Mobil 1 and the tube than to buy Red Line or RP which both come with the modifier.

For the OP, you need one quart front and two for the rear, your choice on brand just be sure to add the modifier if needed. If you tow you are supposed to use 75w-140 in the rear. I did not need a pump or funnel but that depends on the shape of the bottle. I find that mobil 1 and RP bottles fit in the space better than a bottle shaped line Red Line. Also clean off the magnet on your drain plug while you're in there.

Edited, since I can't read.

 

I thought with factory limited slip you need a special mopar additive on top of the gl580-90 or 75-140 syn.

 

I hear an echo. Some synthetics come with the "additive" aka friction modifier. You can buy the Mopar one or autoparts stores sell it too at a cheaper price under a different brand.

 

there was some delayed action for some reason. I swear i posted my question before your previous answer even tho according the time posted you had already posted the answer before I asked it lol not sure how that happened some time warp..