Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 291-20661 found under Lock Valve Spring Retainer by Curtis Engine And Equipment Inc. The National Stock Number assigned to this part is 2815001928767, and the Federal Supply Class is 2815 Diesel Engines And Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 291-20661.