Vent Tube on Gas Tank

You have to be careful, because you can create a siphon. The original tanks would only siphon if you filled them completely up to the filler cap!!! in the neck, but then could only siphon down the filler neck "several" inches. That's because that is where the vent attached, and the neck acted as a siphon breaker.

That's what I would do--- duplicate the 69/ earlier vent.