Someone has added a second source of fuel-out or -in to the tank for some reason, since theres nothing there as-stock. If you have your rear window glass removed as recommended, pull the gauge sending unit out and with an explosion-proof flashlight, look inside to see whats been done. If the thing is loose, I'd remove it and either fix the threads or plug the hole, as fuel leaks that close to the header is serious business!
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