Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number M51 MODIFIED found under Muffler Aircraft by Electric Boat Corporation. The National Stock Number assigned to this part is 1560013056924, and the Federal Supply Class is 1560 Airframe Structural Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like M51 MODIFIED.