This is no secret , and I`ve posted it a few times .
U CAN RUN A VENT LINE UP IN THE TRUNK, MAKE TWO COMPLETE CIRCLES/360* LOOPS , BACK DOWN THRU THE FLOOR TO UNDERNETH THE CAR ,WILL WORK IN A ROLL OVER , WILL VENT UR TANK W/O FUMES IN THE CAR , upright or not..
I run one on my 68 fastback , doesnt puke gas out when filling , like the brand new 68 barracuda I had when I was a kid .