Did you only look for an indentical tank, or...
one that will fit the space? 'Cuz while it's unlikely you'll find an exact match for the tank, you should be able to find one that'll fit the space that's close to the same capacity. If not, what about other spaces? Just 'cuz the factory put it somewhere doesn't mean it has to go there...or that the original location is even the best place for it. It's highly possible that another location will be much easier to plumb to.So time to think outside the box.The only other suggestion is a custom welded tank, which will cost you at least twice as much. The only source I know of that makes a good quality welded tank is C. C. Tech (http://www.gocctech.com/marine/boat-tank.htm)