Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number RV-40 42B USED ON S N 55901-4 found under Cover Hydraulic Pump Motor by The Walter Machine Co Inc. The National Stock Number assigned to this part is 4320013482600, and the Federal Supply Class is 4320 Power And Hand Pumps. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like RV-40 42B USED ON S N 55901-4.