A 94' GC Full time 4x4, 5.2ltr. I want to change the T-case fluid, what type of fluid do I use, I am concerned becuase of the VC coupler, don't want to trash it.

Check your glovebox manual, The fluid types should be in there.

the manual says DexronIII/Mercon Automatic Transmission Fluid.
but I would go with a Synthetic lube thats equivelent to Dexron III/Mercon I recommend Royal Purple