[dflarsen77]

If you don't want the tank to siphon itself empty, your 72 should have a rubber line coming right off the sender (I think they do anyways). Pinch it off completely with some kind of clamp (fuel is the fatter one), and it only leak out what's in the whole line. If it doesn't have that hose, you can just take the sender out. Same idea of taking away the source. Then I recommend replacing all the rubber lines unless you've done them yourself recently.

Although now that I look at your pic more, it looks like the one leaking is your vent or return line, the skinnier one. Either way, the idea is the same, cut of the source, replace the rubber lines. And don't take a smoke a break while you're doing it!