The transfer case is located directly behind the transmission....it's what your driveshafts connect to (long round tubes going from t-case to the front / rear axles).

The front differential is harder to drain the oil, my recommendation is to take the skidplate off and get a good allen wrench to fit the plug. I broke my 3/8" ratchet on mine, but the plug came out <img border="0" title="" alt="[Wink]" src="images/icons/wink.gif" />

Good luck.