WHAT SIZE Fuel Sender??

I'm in Florida, buying some parts for my 67 Cuda in NY.......Don't have the car to check some stuff first.........

What size fuel sender would I have with a stock 273 2 Barrel motor?.......5/16 or 3/8 ???????

I'm assuming it's a 5/16.......BUT, when you ***-U-ME, ....( you know the rest of the old saying, right?)8)