Used on 2hp centrifugal pump 4xz16 nsn 4320-01-506-2047. right-hand 20 thread quantity per inch stainless steel acorn nut 7/16-20 for centrifugal pump repair part for centrifugal pump 4XZ16 nsn 4320-01-506-2047; stainless steel; 7/16-20; also called acorn nut