To add or not to add friction modifier?

[rfitzgarrald]

I am getting ready to install a Mag-Hytec diff cover on my 2007 mega-cab 3500. I'm a little confused. I've been told that since my truck has a limited slip, I need to add the limited slip additive. The owners manual says to use GL-5 SAE 75W-90 synthetic or equivalent. 2500/3500 axles do not require limited slip additive.
I just purchased 8qts Valvoline synthetic 75w90 limited slip gear oil and 3 4oz bottles of friction modifier from the local dodge dealer. Do I add or do I not add?

 

[seafish]

Your 2007 AAM diff uses a torsional style gearing to achieve its limited slip…it does NOT require LS additive with the gear oil.

 

[rfitzgarrald]

Seafish, thanks for the response.

 

[Cummins12V98]

Highly recommend AMZ/OIL SevereGear 75/110. About 55K on the AMZ/OIL and 65K on the truck towing 29K with 3.42's.