The filter is from the sending unit .The spring i believe is a anti siphon spring that used to be put inside the filler neck to keep people from stealing gas ,it made it hard to run a hose into your tank .
Well would you look at this ! While looking for parts in my parts bin ,i found a new, still in the package anti siphon spring This one has to be from 1971 ,it came in some parts i bought a few years ago from a Ford dealership that closed in 1971.
Horse, You're probly right but what puzzles me is that old spring doesn't look narrow enough on the small end to block a hose like the one in your package, unless something goes on the end of the spring too