We used to write about our old Kyosho Landmaxs over at rc car action. There is a thread there about your car: http://radiocontrolzone.com/showthread.php?t=35901
Granted it is a year old, and you may have to wait some time for a reply, I am sure there will be plenty of people that would have parts laying around.
I have the fuel tank BS-65, used? I assume you are in US?