Hi Gary,
I am working with a client with a very similar problem.
Questions:
a) Were your autosave files for this project still there after the others went missing?
b) Did you have any luck with Data Rescue II or File Salvage? If so, would you elaborate?
c) Have you run DiskWarrior on the external drives, and if so, did that help?
If possible, please email me back your reply also at TheMacTechGuy at gmail dot com.
Thanks.
Larry