Usually, instead of a lever actuated float (as in a street car), there are cylindrical floats or resistor level sensor "columns" bolted onto the top plate. Like this one: http://image.customclassictrucks.com/f/techarticles/1304cct_1968_chevrolet_c10_camaro_gas_tank_install/43931456/1304cct-04-o-%2B1968-chevrolet-c10-camaro-gas-tank-install%2Bfloatless-fuel-level-sender.jpg The lever action floats move around too much when the fuel is sloshed around and do not allow for the foam (which dampens that slosh) to be used, so you cut a "column" in the foam vertically and install one of these floatless senders, making sure of the seal on the header plate of the fuel cell.
