Wish I could tell you what a '69 is like, but on my '58, I remember removing the neck from inside the cab, then lubricating the neck pipe with some vaseline. That allowed me to slip the grommet on. From that point, I put the grommet/filler pipe into the thru-hole and incrementally adjust the pipe/grommet so that the grommet fit back into the hose in the cab that goes to the fuel tank.
Bill
