colin, have the dealer check availability of a reconditioned ICU for a 300SL. It is identical, and the MBUSA parts system seems to defer to that model. If there any MBCA members in your area one of them may loan you one from a running vehicle for test purposes. Our local indie told me years ago that it is critical to maintain all ignition system components of the 104 engines to prolong the ICU's life.

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Fred Hoelzle