AC Delco plugs are in Germany arround 10 Euro or 14 bucks each. Livetime is, if you do not exceed the glowing time, close to unlimited. Those with registor beforehand are 2.8 Volt plug without regulator built in. The 24 Volt plug, which do not fit to the connecting shoes of the CUCV series trucks, are 24 Volts with built in regulator. There are also 12 Volt plugs available for the civilian 12 V series trucks (Engine code J or C). Of These I do not know the specs., whether wit or without regulator built in.
Wolf