This has the same system as my 91 300SL. One ignition coil behind the left headlight area and a distributor cap on one of the cams.

None of these would cause the problem you have.
Don't bother looking at the spark plug end of things yet, use the ignition wire from the coil to test for spark. ( the one that runs from the coil to distributor. ) Use a spark gap and don't hold onto any metal.

DO NOT USE A MULTI METER TO CHECK FOR SPARK WHILE CRANKING AT MINIMUM YOU WILL DAMAGE THE METER. THERE IS ALSO A RISK SEVERE INJURY / DEATH.

You can use the ohms function to check for a broken coil wire when both ends are removed and away from the car.

I{f you are not getting spark from the coil , everything past that isn't important at this time.

If you have a very weak heart, possibly. There may be 25 KV at the spark plug but almost zero current.

The overhead cables on the trains here are at 25 KV but with immense current. Almost certain death there.

RayH

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

I am getting power from the coil to the end of the coil wire and in to the distributor. 6v, and I am certain of this. It is one of the things I mentioned in the first post.

Unfortunately we have already looked for both cars, reman and new, through MB and had no luck. The $500 reman option on ebay is the way to go it seems.

This is his only car, and sadly he nor I do not have the time to keep at it right now so he is having it towed to the shop on Monday.

I'll keep you all posted with what it ends up being.