baja,

The series (loop) plugs are ~1.5 volts each. The resistor wires and the GP indicator in the dash drop the 12 volt battery voltage to about 6 volts for the GP. What a waste of energy. Maybe the pencil tip GP were not available earlier, but 12 volt loop GP could have been made to eliminate the resistors.

I wonder if these series plugs were left over from 6 volt systems or used in an 8 cylinder 12 volt system.

It sure took MB a long time to update to the paraller (pencil) GP. I can't believe MB changed some MB engines to parallel plugs and not others.

P E H