Hey Trooper-san,
Just went through the same thing with my head. You have removed everything you need for the unit to come off. Mine was stuck on their pretty tight, just took some effort and gentle tapping to loosen everything up. At first I thought I had missed a nut/bolt somewhere but it is just those 8 that you already removed. I know what you mean about that one nut, it was a real pain to get off. I still don't know about getting it back on. How are you supposed to re-torque when you can't get a torque wrench on? I also would be interested in others advice/input on this. Good luck!
Cory