Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number D-983 found under Valve Check by Insinger Machine Company The. The National Stock Number assigned to this part is 4820011974743, and the Federal Supply Class is 4820 Valves Nonpowered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like D-983.