Vented or not vented ?

Hi everyone,

I have a 1970 Plymouth Sport Fury, and the gas tank has 2 rear lines. Both are vent lines, I know that already, from the FSM. I'm missing the short line, I have only the bigger loop line that goes in the trunk (I suppose I could just cap the shorter output).

Just to be sure: it means that I can use non-vented gas cap, right ?
Author: Chrome58