This is a brand starter drive assembly for tractors. This fits on models: 1800 SERIES, 2000 (4CYL 62-64), 2030, 2120, 2130, 4000 (4CYL 62-64), 4030, 4040, 4120, 4130, 4140, 501 SERIES, 600, 6000, 601 SERIES, 650, 660, 701 SERIES, 800, 801 SERIES This replaces part numbers 87421556, C1AF11350A, D8NN11350CA, EC0N11350CA. Tech specs are as follows: 9 tooth, CCW, 29 spline, 15.9mm ID, 123-140mm L, pin mount, 21.5mm pinion length. Locking barrel design Thanks For Your Business!! 1100-0307