For the pre-23', look up the 2018 Gasgas Contact oem chassis parts list. The tank "kit" costs $330 USD and adds about a liter, bringing the total capacity to 3.5L. It includes the weather strip tape and adhesive heat shield. New oem petcock is only another $10. Use a fuel hose clamp (screw type/non-slotted) or oem crimp-on. Swapping between tanks only takes a minute (1 screw). There's even a no frills Contact tank sticker for an additional $30...