There are several TSB's out that cover transmission issues. They are both covered in the following topic although the title involves one that just is a re-flash of the program and requires no parts.
http://www.lostjeeps.com/forum/phpBB3/vie ... php?t=6761
The second one involves parts but one would not think they would be parts that take a while to order. The two parts include the trnsmission filter, then later the sump filter was added. A topic on that issue is as follows, but some who have had this done still are experiencing the shutter. This covers specific transmission build dates and you need to get the number off the transmission (crawl under the drivers side to find it) to see if yours is in the range.
http://www.lostjeeps.com/forum/phpBB3/vie ... php?t=7918
Finally, some of the transmissions in the above group have lost their torque converters and that is covered under a third TSB that you will need to search for if it is not already buried in one of these. Interestingly, I seem to recall that TSB did not mention specific build dates or previous TSB's. It would seem to me that perhaps your dealer would be ordering a new torque converter if the parts are taking this long.