To reinforce beltfed's advise. If you have the OEM tank you likely had a baffle break loose. My '38 has all the baffles in place and it'll move 1/4 tank going around corners and up hills. My '53 isn't as bad but moves around some. It's easy to test your sending unit.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.