^^They are incredibly simple. A fitting welded into the filler tube connects with the vent tube, which goes up high against the rear fender top surface, makes a "U" and feeds down along the filler tube and through a hole in the trunk floor gasket. It terminates, open, inside the frame.
what you are doing, by running it up high, is if it is ever so full, such as full up into the filler neck, and parked "that side down" on a hill, the fuel might actually expand and siphon. but as soon as it removes enough to break air into the filler neck, that breaks the siphon