The project I'm working on isn't boat related, but I'm about 75% sure they originally used either a Magnaflow, Jabsco, or Neovane pump. Dig out those pictures,,,, I need to figure out what pump was used and how it was plumbed, and the more pictures I can see, the better.
It's hard to see, and this is the best shot I have, but it is belt driven off the lower blower pulley.
http://www.***boat.com/image_center/...otgun_pump.jpg