Valve mounts to fuel tank with 2 screws. Tractors: 501, 600, 601, 700, 701, 2000 (1955-1964), 800, 801, 900, 901 (prior to s/n 126524, with 1/4 inch fuel line) (gas engines, 1955-1960). 501, 601, 701, 801, 901, 2000, 4000 (diesel engines 1958-1964).