I need to make changes to my '57 truck to prevent fuel vapor from exiting the tank. I'm looking for an "anti-surge" or overfill protection valve to install in the filler hose (not the vent). If a vehicle has one of these valves you can usually see the green or white "ping-pong ball" in the fill path somewhere when the tank is dropped. Does anyone know of an application with this in the filler neck? Or does anyone know of one that installs inline? I seem to remember seeing one on a marine site but I can't find it now. I can only locate the valves that install in the vent hose. Finally, if someone has one sitting around they'd like to get rid of that could be an option as well.

TIA