NEW (Not Rebuilt) Cast Iron Carburetor Fits John Deere 1020, 1520, 2020, 2030, 2510, 2520 Tractors | Cast Iron; 1-5/16″ ID throttle throat, 2-1/16″ OD choke (air horn), 2-11/16″ mounting pattern, 1/8″ NPT fuel inlet | Replacement Numbers: John Deere AT23000; Carb Numbers: TSX904, TSX905, TSX905SL, TSX944, TSX944SL, TSX945, TSX945SL.