Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number RV-40 42T USED ON S N 55901-4 found under Ring Piston by The Walter Machine Co Inc. The National Stock Number assigned to this part is 4310013482530, and the Federal Supply Class is 4310 Compressors And Vacuum Pumps. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like RV-40 42T USED ON S N 55901-4.