On this early under seat gas tank there is no sending unit with float being reproduced! Therefore, with a little American ingenuity there is a way to nicely solve this problem.
Obtain a now reproduced sending unit from a 1939-46 GM truck. The float rubs the tank inside so something must be done.
Turn the top 5 hole disc so that it’s humps (where the electric wire attaches) so that it is pointed to the 10:30 position on a clock.
The two top holes in the disc line up perfectly with the hole in the truck’s tank.
The more bottom three holes are now just slightly out of position.
With the side of an electric drill bit or “rat tail” file three holes to make them slightly oval.
Now just tighten these three screws into the tanks original holes with the gasket in between. What a nice not seen modification!