I won`t pay $400 that is asked for rear diff oil change. Lube shop offers good price and they stock Delo Synth. Do you use Delo 75-90?

you can do it yourself in about 10 min.
i just did both mine today front rear and t-case in 33 minutes.
delo is a good oil. any that meat the GL-5 will be good. if you have limited slip then you'll need a bottle of the additive.

When did our limited slips start requiring additive?

Thanks Killer.

This is what I used when I changed the rear differential in my truck.

AMSOIL Severe Gear® 75W-90

Also, copied & pasted from my 2012 owners manual:

Front and Rear Axle – 2500/3500
Models
Synthetic, GL-5 SAE, 75W-90 or equivalent. Limited-Slip 10.5/11.5 inch
Rear Axles Limited slip additive is not required.

I put it it my truck, The company I work for uses it in our semis and change it out every 2 years regardless of miles and I know they are putting more miles on there semis in 2 years than I am in 7-8 years.

You are correct, the newer AAM axles don't need the additive.

They don't require additives as they have no clutches. They are a gear type LSD.