I've got a green 919 tank for sale, in pretty good shape. A bolt rattled out and cause a vacuum in the fuel line, resulting in some dimpling in the right side of the tank. I've attached pics so you can see the effects. Tank only, not gas cap or sender unit.
Clean inside, too. Get it to repaint, to experiment with, or to replace a rashed tank for about 1/3rd of the cost of a new one.
Asking $200 OBO + shipping from Oakland, CA.