Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number D1597 AND D1598 found under Core Assembly Fluid Cooler by Xchanger Manufacturing Corporation. The National Stock Number assigned to this part is 4420013086753, and the Federal Supply Class is . Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like D1597 AND D1598.