If your leak leaves a few drips rather than a puddle, I wouldn't worry about it. When I first got mine, it left a really good puddle. In this day and age of vehicles that never leave even one minute drop of oil, it was quite alarming. I investigated and It looked like I had quite a few things contributing to the puddle, so I checked the level and refilled often on both transmission and transfer case until I could tear into it. On the one leg of the TMC'09 convoy, I travelled about 150 miles and had to put in about 1/4 pint afterward to top it off.
I eventually pulled the transmission and transfer case and found I was missing the gasket on the front of the transmission case and the cork bearing seal on the front transmission shaft was cracked. I also found a hole in the thimble sized oil retainer cup that covers the shifter rail near the top front of the transmission. I replaced that, put in a new bearing seal and I put new gaskets on the transmission front and top (cover plate). I used silicone sealer on all bolts (since the threaded holes go completely through the case). The yokes on the tranfer case, both front and back, were worn so I replaced both of them and their respective seals. When you replace yokes, be sure to use sealer on the splines and the nuts/bolts since that is a source for oil to escape too. Here's a link to my post on this subject http://www.g503.com/forums/viewtopic.php?f=4&t=143261
Now after this, my jeep leaves only a drop or two - definitely not enough for a puddle. I don't know of many who can claim their jeep doesn't leave at least a drop of oil , hence the common phrase "marking its territory"
BTW - gear oil smells way different than engine oil so you should be able to easily tell if your leak is from the engine or the transmission/transfer case. Just open up a container of gear oil and a container of engine oil and take a whiff of each, you'll see what I mean. Get some of the leaking oil on your finger and sniff - voila! You should have your answer (unless both are leaking