Gas Tank Overflow Problem

I am sure someone out there knows the answer to this. My 1972 Demon has a fuel overflow problem.

When I fill her up at the gas station the pump will not automatically cut off when the tank is full like it does with newer cars. My Fathers '66 Coronet has the same problem. I spoke to him about it and he explained to me that the new pumps have different pump nozzles than old pumps and that the fill tube in these old mopars don't have the little flappers that kick the pump off. He writes his mileage down and keeps track of when and how much he needs to fill up. He thought someone out there probably made a little insert that would go into the fuel fill tube that would kick off these new pump nozzles.

Has anyone ever had this problem and corrected it? I'm tired of splashing fuel on the side of my car and think that there has to be a better system than listening for it to gurgle when its closed to full and jotting down the mileage.:banghead: