Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 1MR3172 found under Switch Lock Ignition by Mack Trucks Inc. The National Stock Number assigned to this part is 2920000647750, and the Federal Supply Class is 2920 Engine Electrical System Components Nonaircraft. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 1MR3172.