Rear trans seal - 4000Q

[Hoffman Anthony J A1C 552 CMS/MXMVC]

I have an '87 4000Q which needs the rear trans seal replaced. That's the one
on the back of the center differential. The "cup" for the driveshaft doesn't
have a bolt in the center, so I'm not sure how it comes out. 
 
Anyone have any experience replacing this seal?
 
Also, what type's of synthetic fluid are recommended for it. It has the
original O16 with the manual locking center differential.
 
Tony Hoffman