Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 1W501 found under Ring Piston by Caterpillar Inc. The National Stock Number assigned to this part is 2815014265010, and the Federal Supply Class is 2815 Diesel Engines And Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 1W501.