Where does the Fuel Gauge sending Unit get it's Ground so that the Fuel Gage Works.

I'm putting in a new fuel tank and fuel gauge sending unit in my 73 Dodge Dart Sport. There's only one lug on the body of the sending unit and I'm thinking that the sending unit needs to pick up a ground somewhere for the gauge to work. Does the fuel tank tied to the chassis provide the ground? Thanks for any help.