As I recall, the screw pattern allowed for installation in two positions. I installed my new tank and sender in 2021 so I can't remember exactly. It seems like I stuck it in two different ways and chose the best one.

I could be misremembering completely, though.

Here's the original tank. It has a keyway.
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Last edited by Otto Skorzeny; 02/08/2023 5:32 AM.
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)