AR58172 AR50392 Damper Tractor Crankshaft Pulley Fits John Deere 4000 4010 4020One New Aftermarket Replacement Crankshaft Dampener Pulley Fits John Deere 4000 Series Tractors This single groove crankshaft dampener pulley mounts at the front of the engine and absorbs torsional vibration from the crankshaft, protecting the engine and belt driven accessories. Designed Fits John Deere 4000, 4010, and 4020 tractors equipped with diesel engines and without air conditioning. Verify that your tractor does not have factory A C before