On my 70 Charger the vent tube clipped on the main filler tube, then ran into a small trunk floor grommet, into the frame, then attached to a rubber vent line that went on a single vent nipple on the tank sending unit, the upper part of the vent tube followed upward to the filler cap, then promptly took a 90 degree turn with a short rubber connector into the main filler tube, just below the flip cap, under the rear qtr

mike