For my 47 Cadillac fleetwood 60 special, what are the sizes of the flare nuts for the fuel line to gas tank and fuel line to engine bay?
I have no experience with the '47 but I noticed nobody else has answered after quite some time. Normally line sizes have one associated very common fitting size. In the rare case it's not the standard for the line size, most common place I've seen is on a brake line near the distribution block, the oversized fitting is normally obviously oversized. Do you know the line sizes? Do you have the parts off the car? Can you measure them now?
If nothing else maybe my reply will get your thread noticed by someone else with something closer to a '47.
Good luck,
Scott