Hi Alan. I found a site with hundreds of different rubber bellows that 
  are available for use as covers for automotive power steering units and CV 
  joints. They have pictures with dimensions for each model.
  I simply picked one that fit the actuator body and rod, looked up what 
  car it fit, and went down to the auto parts store and picked them up. I think 
  the were about $14 each.
  My files are still packed away as I have a huge pile of unpacked boxes 
  from the move to Florida but sooner or later I'll get to that box and be able 
  to post the link to the bellows site.
  As for the link on the shaft, the stainless 1/2 inch rods I fabricated 
  just slide through the end of the bellows, then attach the actuator, slip the 
  bellows over the actuator body, and clamp and seal both ends of the bellows. 
  If it works as designed, I should be able to switch out an actuator in about 
  15 minutes.
  Keeping a full dive plane/motor/actuator assembly nearby as a spare will 
  mean little down time should I crash into something and smash it all to 
  hell.
  Frank D.