[Roadtrip]

I believe standard 8mm hose will do and is commonly available. Just take a piece of the old stuff up to any auto parts store.

The component on the top of the front fuel filter you refer to is the pressure relief valve in the return line from the injection pump. If the pressure in the line prior to the injection pump exceeds 17 psi, that PRV opens and vents the excess pressure into the return line and back to the fuel tank.

BTW, the easiest way to change the front fuel filter is to remove the filter assembly altogether from the frame of the car and do it on the workbench. It's a little easier to clean out the seal retaining groove and center the lower housing for proper alignment during tightening.