So, a funny thing happened the other day. I recently got an '89 burb 4wd with a 4-speed AT and a NP 241C transfer case. I was changing out all the fluids for the first time. The Haynes manual I have said nothing about how to change the transfer case fluid, nor does the owners manual (other than you should change it periodically), but how hard can it be, right? I found two bolts with 1-3/16" heads in the side of the case, one at the bottom and one midway up. "Aha," sez I, "drain and fill plugs." Well, I took the upper one out, and about a quart of what is apparently transmission fluid came pouring out onto the driveway!

I can find no other apparent fill plug on the case, nor can I find any other apparent use for this bolt. So, I got the drain pan, pulled the lower plug, drained the remaining fluid from the case, and refilled to the upper plug with about 3 quarts of ATF. It shifts into 4wd and back normally, though I have not put many miles on the vehicle since the change, and everything runs quietly.

After getting the usual helpful advice from friends ("Maybe you're supposed to roll the truck over before you fill the case!") I've decided to turn to the experts for help.

How did all that fluid get into the case? Could I have a bad seal between the transmission and the transfer case that is allowing ATF to be blown into the transfer case? Or is there a fill plug somewhere else I should be looking for? Did I just drain my transmission through the transfer case? (Transmission fluid level does not seem to have changed. Yet.)

Thanks in advance for any help.