Not certain if it was original but doubt it. Instead these were very popular to keep people from siphoning fuel during the "Gas Shortage years.
Just have to use a small hose or push it into the tank
I under stand if your doing that sort of thing though it can get stuck (outer ring of the spring and the edge of the gas tank fuller neck) I understand
Might be one of these stretched out but will look through pictures to see if I can find anything there showing one