Oregon 34-826 Flat Idler Pulley Replacement for Murray 91179, 421409 Flat idler pulley For transmission drive tension/clutch Outer diameter: 3-11/32", Flat outer diameter: 3-1/4", Flat width: 7/8" For 38", 40" and 46" lawn tractors Overall width: 1", Bore: 1/2", Offset: none