Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 684 401 C91 found under Cylinder Head Diese by Navistar Intl Corp. The National Stock Number assigned to this part is 2815010106126, 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 684 401 C91.