One of our base owner recently converted the electirc head on his Catalina 350 to fresh water flush, I thought I'd share how he did it here:
http://blog.windpathboatclub.com/2009/03/conversion-of-windpath-catalina-350s.html
http://blog.windpathboatclub.com/2009/03/conversion-of-windpath-catalina-350s.html