Modern gas pumps flow much faster than pumps from the 70's. And the design of the filler neck is not the best design and often causes the pump to click off early. If you put in like $12 and the pump clicked off, it may have clicked off way too early and what you thought was full was only a 1/3 or 1/2 a tank full. I'd go to the station and pump it full slowly until it was for sure full, and then see what the guage says. I've never seen a float fall off myself. Filler up to the top and see what it says ... that is what I would do.
I probably will do that, but the only thing I worry about is, IF the gauge still reads way low, then I have 15 gallons to drain! lol.
