Replacing the fluid in transfer case?

I haven't been able to get a clear answer on what fluid to use for the Vehicross's transfer case.
I read some on gear oil, transmission oil and others. (I'd like to get the most premium)
If I could use transmission fluid, would it hurt to add in Lucas Oil as well?

From the shop manual:

TOD system DEXRON) -III Automatic transmission fluid.

Not sure about using Lucas in the TOD...I just use a good quality synthetic transmission fluid.

I wouldn't put additives in a fluid. The more heterogenous the mixture, the more prone it is to sheering/breakdown. I think I've been using Valvoline full synthetic Dexron VI for nearly all of my trans changes for several years.

http://www.valvoline.com/our-product.../dexron-vi-atf

I don't know about the finer points of how these full synthetics are made--and which brands may be superior to others...but I swear by this stuff. every 15k. Full flush/change every time. Comes out as pink as it goes in.

I do the same thing with Shell Rotella-T6 full synthetic & 3000 mile oil changes. Religious changes. No problems. I've been checking my fluid every fill-up, and I don't appear to be burning any at all. *knock on wood*.