Clean the back of the tractor where you can see the level of fuel in the gas tank.They are available for about $20. It is the type that replaces the fuel cap and has the gauge in the top. If you are thinking about an electrical gauge then you would have to find a tank that comes with a sending unit built for it. Most of JD's fuel tanks are a peculiar shape and a normal symmetrical unit will not give accurate readings. And then there is the issue of how to install it into a tank if you try to use your current tank. You will have to cut a hole in the top of your tank and install the sending unit and then make sure that it does not impact the seat/fender. If it were me for the meager benefit that an electric gauge would offer, I would buy the screw-on cap style and call it a day.