I disconnected the wire to the sending unit stud and connected a jumper wire to the stud and the other end to the ring connector. Fuel gauge immediately registered accurately.

So, I'll either leave that stupid jumper in place (not really) or I'll scrub up the stud and ring with a brass brush and see if that helps.

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)