Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 5B6172 found under Washer Blank by Caterpillar Inc. The National Stock Number assigned to this part is 5310014715093, 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 5B6172.