NOS A Body Fuel Sending Unit #2932960/#3621615

Is the part # stamped on the the sending unit?
I have a NOS sending unit. The part number on the box label is 2421493
This was the part number that showed up in the factory parts books from 1963-67.
In 1968 and later the part numbered changed to 2932960.
I'm not sure what or if there was any change to the actual part?