This is a complete engine overhaul kit for Allis Chalmers tractors. Complete kits contain sleeves, pistons, rings, pins, complete gasket set, main bearings, and rod bearings. *Please specify bearing sizes when ordering* This kit is used on models W, W25, WC, WD, and WF all with the 201 CID 4 cylinder gas engine. This is a 4 1/8" overbore from the standard 4" bore. Be sure to add me to your ! Thanks For Your Business!!