Drained transfer case fluid instead of oil!

So I did something stupid while changing my oil (98 Durango)...I unscrewed what I thought was the oil pan plug, but was (I determined after some research) actually a plug on the transfer case. Some oil came out. The confusing part is it wasn't the transfer case drain plug, it was something else...I can't figure out what it is (it's the bolt with the arrow pointing to it on the diagram below). I tried to check the fluid level using the fill (or drain) plug but it was too tight and I couldn't get it loose. Also, do you only use the transfer case for 4-wheel drive? Assuming there is now not enough/any lubricant in the transfer case, is it OK to drive with only 2-wheel drive?

Any help appreciated (I can even handle a couple of "that was really dumb"s)!

http://i835.photobucket.com/albums/zz280/kmac322/transfercase.jpg?t=1260745402

Call this a blessing in disguise, because it will force you to get the fill and the drain plugs operational.

First of all, regardless of whether you are in 2wd or 4wd, transfer case components are turning whenever the vehicle is moving, so you need oil in there all the time.

Next, you should check the transfer case fluid level AND the level in the front and rear diffs at least at every oil change. So, if you are doing your own oil changes, then get the correct socket to fit the plugs. The fluid level needs to be right up to the bottom of the fill plug.... that is, you fill the case until fluid starts coming out the fill plug hole.

Finally, when you get the correct socket, drain the remaining fluid from the transfer case and refill it with fresh fluid. This is good preventive maintenance and should be done every 2 or 3 years anyways. Check your owners manual, but I think it uses automatic transmission fluid.

OK I'll do that, thanks for the response.

Any idea what the plug I indicated is for? It's not the drain or fill plug...

i dont know for sure what that one plug is but i can say that transmissions ans transfer cases have plugs in them for other reasons then just draining. some of them hold spring and detent balls, test pressure at different points,acess holes, adjusting/holding shift bands, some plugs are left over machining holes, or are left over from an old design or different application that does not appily to your vehicle. i would personally not worry about it. as long as the plug is in, check and top off the fill level and call it good.

That plug hold the transfer case shifter detent ball in place.