Been long since I took the tank off and am now reassembling with a new tank. Same as the one that came out. I do not have the vent lines and will replace however I am not clear on the theory. One line appears to stay under the floorboard. The other rises up through the floor, turns left towards the left rear wheel, up and down. Appears one is higher than the other. not sure if the outlet is same height. My understanding is that 1968 (300) is a vented cap. Under hard throttle, the fuel would be forced perhaps, into the filler tube causing a blockage of the vented cap. Air would then need to enter the tank through one or both of the vent tubes. I will try and bend my own however just needing to understand the theory so I don't go too low or high or situate the lines where they could plug with debris. Also, are ends open? Restrictions? Is there a better way of venting, perhaps using canisters? Thanks.