Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 521819 found under Coupling Half Shaft by Smiths Detection Inc. The National Stock Number assigned to this part is 3010002031472, and the Federal Supply Class is 3010 Torque Converters And Speed Changers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 521819.