Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number W520403S442 found under Nutself Lockinghexagon by Ford Motor Company. The National Stock Number assigned to this part is 5310016791088, and the Federal Supply Class is 5310 Nuts And Washers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like W520403S442.