Yup! Thank you both for the detailed explanation!
I was under my X yesterday, Let me repeat to be absolutely sure!

I assume the X-drive that I am referring to is the transfer case. Either model have the transfer case, it just depends if it has x-drive capabilities, and each model uses different oil.

I am able to locate my rear differential, but I can't find the other one? is it above(under) the aluminum skid plate. I assume it will use the same oil as the rear.