Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 545-8170-21-8A found under Bearing Assy Cross by Chief Of Engineers. The National Stock Number assigned to this part is 2530006930986, and the Federal Supply Class is 2530 Vehicular Brake Steering Axle Wheel And Track Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 545-8170-21-8A.