Hi,

Just some innocent questions that comes from wonderment!

Are you listening from the gas tank fill pipe with the cap off?
Some people, with old ears, use a short piece of garden hose stuck through the unleaded flapper.

The pump inside will be really quiet, if the tank has a lot of fuel in it.
The pump itself sits in a baffle that looks like a stainless steel bowl is in the very middle of the tank. This too can block some the sound from getting up to the filler pipe.

Just your thinking of very old pumps is a valid thought.
The in-tank pump usually does not out last the main pump.
Plus there is a rubber hose connector in between that fails too!
When I have my car up on a car lift the pump it possible to listening it from directly beneath the very center of the tank.

I know, doing a crawl under the car does not look or feel cool, but hiding in the trunk, to change out that pump that might be working, could make one hot! (:-)

Phil