Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 63-889-021 found under Gear Set Spur Match by Dresser Industries Inc. The National Stock Number assigned to this part is 3020014856643, and the Federal Supply Class is 3020 Gear Pulley Sprocket And Transmission Chain. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 63-889-021.