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 D10 to s/n 3500, D12 prior to s/n 3000, D14, and D15 all with the 149 CID 4 cylinder gas engine. This is a 3 9/16" overbore from the standard 3 1/2" bore.Be sure to add me to your ! Thanks For Your Business!!