http://sandiego.craigslist.org/boa/337206369.html

What is it?

I think that guy just has an old Berkeley TA and an old hamilton or buehler or some other axial flow pump laying together, not to mention the v drive stuff.

Now here's an old Berkeley for ya!

early 60's.
When they came out they picked up the nickname 'the toilet seat' for obvious reasons. lol

heres some more pictures (which i stole from another site  ) of the pooper pump....









How it works:

From what I understand is the 'toilet seat' lookin part moves left to right to steer, but im not quite sure how reverse works. It almost looks like the 'toilet seat' drops down so the jet is hitting the 'ribbed' part of the 'toilet seat' just above the jet outlet and the water redirects down the sides and to the curved part directing the water flow in the reverse direction. 

Its amazing how the engineering of the berkeley pump reinvented itself to todays much simpler/efficient design