How a shaft drive bike rearend mounts and works?

[ROD]

Cant get my head round this at all and its bugging me!...so some Q's.............dont laugh!
 Can someone please explain how the set up works? I cant seem to fathom how the prop connects to the shaft.
 Whats the large diam tube that seems to encase the uj for?
  Also does the prop uj have to be on the same pivot line as the pivot of the swingarm to prevent binding as the swingarm pivots?
 Do different bikes have different drive ratios at the wheel end of the shaft(Im assuming theres some sort of gearing in there to turn the shaft drive through 90 degrees.)

[BikerGran]

Not sure what you're asking, but if it helps at all, there are some pics of gertie's back end (!) on Photobucket...

http://s195.photobucket.com/user/BikerGran_photos/library/GT550%20Trike%20conversion?sort=4&page=1

[ROD]

Thats helpful BG...nice rearend you have there ...oops,back to the thread....I need someone to explain whats what really.