My new tank had a vent line coming out at the top front, I ran it around and up in the trunk, made 2 small coilshi up, and ran it back down thru the trunk floor, that and orig vented flip gas cap have given me no problems, even when filling it. I had a new 68 fastback back in 1968 , that wouldn`t take fuel w/o spitting back out the filler tube , guess it needed more vent even back then. ????