Leaking gas tank filler tubes ?

Thanks for the replies -

Jim, the problem is not at the neck to tank joint. It's supposed to be at the cap/filler tube. I'm not even sure I have this issue, since my car isnt running yet. But caveman's post above indicates it does exist. I figured I'd start asking about this to see what may be up with it, and fix it, before putting my car together.

Dart4forte - did you happen to look inside the tubes to see if there's any differences ? I am certain this has to be a baffle of some sort.

If I were to put a piece of foam in the bottom end of the tube - what kind of foam would one use ? Is this something you can buy from the speed parts houses ? I know that fuel cells use a reticulated (large cell) foam inside them, but where does one get the stuff ?

Cerwin - neat idea with the ping pong ball or "check valve". I wouldn't be opposed to doing this, but if it can be done by mocking what the factory did in the later cars...why not do that instead, whatever the factory did would have to be simpler to install I have to imagine.

Again, I appreciate the responses - keep em coming.

Kind regards -