Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 123-4403544 PART 81 found under Gear Sector Spur by Bethlehem Corp The. The National Stock Number assigned to this part is 3020014438232, 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 123-4403544 PART 81.