Ismalley, check your Owner's Manual for the spark plugs specified for your engine. Modifying resistor spark plugs probably wouldn't be recommended by MB-trained techs. You are correct about the EZL. If it fails the engine will not run, and new/rebuilt ones are quite expensive. That's why you want to maintain the ignition system by-the-book. I take it you replaced the ignition wire from the coil to the distributor cap when you replaced the ignition wires even though it can be difficult.

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Fred Hoelzle