69 Dart fuel system question

have/get a very strong fuel vapor odor in my Dart. At the very top of the filler tube, just inside the qtr panel is a vent tube with a short (1-2") piece of black fuel line hose clamped to it. This hose is open, not capped or plugged in any way.
A buddy in our club gave me a strangely bent piece of hard tubing that he took off of another Dart, a 67 I think he said, mine is a 69.
I could not find in my 69 parts book diagram anything like this tube. It actually fits from the "nipple" to the grommet at the trunk floor where the filler tube goes through.There is no hole in the grommet that would lead me to believe this tube should penetrate there.
Any thoughts or direct knowledge of how this is supposed to be?
It sure does not seem like it should be open for fumes to just collect in the trunk and car interior.