I would assume that the fittings attached by the factory - say, Inline Tube - would be the NPTF for fuel that don't require sealer. Same with fuel pumps, gas tanks, etc.

I have a new tank, steel lines from Inline Tube, and the rubber transition from tank to steel line that cam with the fittings attached. I did not use any sealer on any of these connections and I have no leaks.

1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)