I don't have the part number on hand but on all the vintage stuff we work on we use NGK non-resistor plugs, had great luck with them and they are easy to find.

IIRC its BP5ES and BP6ES.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

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