Mullard NOS GZ33 – 2 used pieces remain. Military and Haltron branded. Another renowned rectifier tube which can often be used as a substitute for a 5AR4 or GZ37 (please check the specification of your circuit before ordering). The mullard really makes a difference in your hifi or guitar amp sound! Brand new in Military or OEM boxes, made by Mullard in the 1950s! Just $149.99 . This is a suitable replacement for any GZ33 = CV5745 Full-Wave Rectifier tube type. Various brands available.