Front and Rear Diff Fluid

[85-BURBON]

I am wondering what the safest option is for my 85 Suburban. It has the 8.5 G80 in the rear and I believe 8.5 up front as well. I am looking into Amsoil 75-110 right now wondering if anyone else uses it? The truck gets dogged pretty hard and I want everything to last as long as possible. I know sooner or later Im bound to break something, but in the mean what whats my best option for front a rear diff fluid???

 

[HotRodPC]

The Amsoil isn't a bad option but I'd ask, How often do you drive through deep water or mud? If you do it very often, I'd think what's more important is changing the fluids much more often to keep the water out of the axles so being the expense of Amsoil, if you need to change your fluid every 6 months or so, then I'd just go with the standard GL4 or GL5 store bought oils. Clean oil is more important than what oil you'll use.