Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 993-149740 ITEM 18 found under Washer Spring Tension by Sun Coast Supply Corp. The National Stock Number assigned to this part is 5310011197206, 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 993-149740 ITEM 18.