Nut and ferrule assembly for thermactor smog tubes. Sold individually, 8 per car with V-8 engine. This is a NOS service replacement nut and ferrule that is one piece. Fits thermactor equipped cars from 1967-71. Including 1967 cars with California emissions, 1968 manual transmission cars, 1968-71 Ford cars with factory Holley carburetors, etc. Several Ford part numbers for this item D5TZ-9B471-A, C6AZ-9B471-A,C8OZ-9B471-A.