Rear differential oil change. on 2002 Chevrolet Silverado 1500

I want to change the rear end fluid in my 2002 2wd long bed 1500 Silverado. Does anyone know if there is a special additive or friction modifier that GM requires when changing the fluid? Can I just refill it standard, stand alone 80w90?

Asked by for the 2002 Chevrolet Silverado 1500
as long as it is not a limited slip or posi rear.