OK guys, don't go get all happy using the wrong line for fuel. Polypropylene line will NOT last with diesel. It is not rated for the temperatures nor the hydrocarbons. Poly line is water or air only. DOT air line is designed to hold truck air pressures and temperatures and to be oil and fuel resistant, not proof. I'll dig out my industrial plastics catalog on Monday and post the recommendations. Nylon 11 is probably the best material, best price stuff to use. It is extremely resistant to petroleum solvents of all kinds, has good temperature and pressure ratings, high abrasion resistance, and bends nicely. PTFE (Teflon) is more chemically resistant, not as flexible, not as high pressure, and cuts easier. It also costs about 10 times as much. I have used literally hundreds of miles of the stuff for paint and air lines in industrial paint shops over the years. The Nylon is the best stuff to use on the fuel system of a deuce that I know of. I imagine DOT air line would be OK in the fuel system in a pinch, but I would definately get the right stuff as soon as possible. A fine stream of fuel on a hot manifold is a real fire hazard, you don't want to burn down your truck over $10 worth of hose.