Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number JD5503-309-31 found under Bearing Roller Cylindrical by Otis Elevator Co. The National Stock Number assigned to this part is 3110001837021, and the Federal Supply Class is 3110 Bearings Antifriction Unmounted. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like JD5503-309-31.