Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 6329453 SZ 4 1 2 found under Heater Convection Steam Hot Wate by Dunham Bush Ltd. The National Stock Number assigned to this part is 4520011555017, and the Federal Supply Class is . Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 6329453 SZ 4 1 2.