Vacuum Tank 1/4" flare end.

Unknown

Just found that my vacuum tank has a 1/4" male flare end fitting and my line is 5/16" with a 5/16" female flare end fitting. The fitting on the tank is not removable. I went to several auto parts shops today and they do not know of a adapter from 1/4 to 5/16. Do any of you know if this is avalable? Only other thing I can do is go from 1/4" to 5/16" with some rubber gas hose but do not really want to do that. PS. Still working on the fuel gauge but got mad and desided I better leave it alone for a bit...LOL. I am sure some of you know what I mean..:) Thanks Ron