I had the same problem, and have lots of experience in taking it
back to the dealer--11 times. Mine was leaking in the "rear output shaft seal". They replaced that two or three times before I asked them to find out WHY it was leaking again. Then they replaced the extension housing (in case of invisible cracks). Then the housing before that. Still leaked. So we tried the entire rear driveline (that was $800 but under warranty). After a few phone calls to DC "customer care" they were allowed to replace the entire transfer case. Funny part is, that when they dropped the case out, they noticed a small vent plug on top. They replaced that little $100 part and it hasn't leaked in over a month.
They wasted:
13 months,
11 visits
over $3000 in parts/labor
7 rental cars (after I called DC)
because they never knew the stupid plug even existed. I begged them to call DC for assistance but they never did. Serve them right. By the way, this is a 5-star dealer, and believe it or not they were better than the first morons I took it to.
Keep after them and make them fix it until it is right. Good luck.
01 HO (still stock because I need the warranty--trust me)