The tank on my '69 is almost impossible to get full. After the automatic shut-off clicks off I can still get 2 or 3 gallons more into the tank if I let the gas run in very slowly. It works st some stations but not all.
It gets very irritating when traveling when you want to get as much in as possible . Also makes it pretty had to ever get an accurate idea of fuel mileage since sometimes a "full tank" is only 15 gallons and other times it is 18.