With the filler tube in the correct position, but the sending unit not lined up with the access cover, you might have a 56 tank under a 55 car. Compare the sending unit mounting location of the 55 tank referenced in JeffB2’s link above to the location shown for a 56 tank shown in this listing.
https://www.ebay.com/itm/1956-Ford-P...-/232981542670
The 55 sending unit is closer to the front of the car.