DO you still have access to the manual on the 6R80? I am looking for the shift diagrams to determine which clutches and planetarys are engaged for 4th and 5th gear. I have a growl when the car goes into 4th and have just pulled the pan and the tail flange checking for possible problems. My Tranny shop still doesn't have an rebuild manual for the 6R80. They have the 6r60 though which is similar.
I have also just talked with Baumann and they say they may have the software in a year or so that could allow them to get there Optishift controller to work the 6R. I have a 5r the needs replaced just like you have been trying to do also.
If you have some diagrams or know where I can get a Service manual disk, I would greatly appreciate it.
Thanks