Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number WS506TYPE3CLASSB found under Spark Plug by Federal Specifications. The National Stock Number assigned to this part is 2920002943747, 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 WS506TYPE3CLASSB.