WOW! I am posting this to help me save it. This is by far the most detailed how to for disassembly and assembly of a 6l90E that I have ever seen! I am feeling pretty comfy that I could convert my 2wd 6l90E to 4x4 if I so choose.
This video is golden!
Part 1
https://www.youtube.com/watch?v=ncD6M1DsnaY
Part 2
https://www.youtube.com/watch?v=reGawHxASCs