sorry, Stretch, just got in from work.

You have a good point about the big main bolt holding the balancing disk onto the crank. After I replaced the old (same that fell off) vibration damper I did notice a wobble in the pulley attached to it. not as bad a wobble as I expected considering that all 6 mounting holes were ovalled and I thought I might have sheared one bolt (later confirmed when I found half of that bolt in the parking lot at my job.

Now, with the damper and pulleys removed again, would be a good time to run the motor for a few brief moments and check visually for any wobble in the balancing disk itself, although being irregularly shaped it might be harder to detect, I'll pick a good high or low spot and hit it with a little dab of paint, I might be able to follow that spot.

I'll look more closely at the installation of the balancing disk and 27 mm bolt for signs of replacement/butchery. I am optimistic that my problem is with the vibration damper not the balancing disk.

I remember you had a poll about harmonic balancer failure. For my failure, which is only partial I would nominate overtensioning of the belts as a possible cause. In the US most of the belts sold aftermarket are slightly too narrow, I guess because the manufacturers want to sell what they are already making giving a nominal metric size to a belt designed to inch standards. The belts continually get looser, and the tendency (I have) is to keep cranking them tighter. after getting in there and seeing how everything goes together I have a lot more respect for the lateral force an overtensioned belt would put on the pulleys and thus on the bolts attaching the pulley/vibration dampener.

From the evidence: 1. non standard stainless steel (dumb) bolts 2. junkyard paint marks on the vibration balancer, this will be at least the second time the damper was replaced.

When I found that I didn't have the part on hand, I really kind of backed off of the job. I was afraid that I would be searching for this part in Europe. I've never worked on a 123 manufactured before 1982 and that was part of my hangup. It took me about 6 weeks of turning this over in my mind to get to thinking that this was a turbo/non-turbo issue rather than a European market/US market issue.

Based on appearance and the feedback from you, vstech and grovert, I'm fairly confident that an earlier US market vibration damper will fit.

If you have easy access to part numbers it could be helpful, I have looked and not found any numbers on the part I have, cleaning it up might help.
The Mercedes people here are reluctant to do anything with a car imported outside their system, but I do have one friendly parts man who might look up the number and tell me what US market cars used it.

To help me evaluate the condition of a used vibration damper, how snug do the 6 8mmx45 bolts fit in the holes through the vibration damper? I only have experience with the two I've removed; the ruined ovalled one is extremely loose fit through the 6 holes, but the presumably good one from my 1982 turbo parts car calls for the same diameter bolts and the fit through those bolt holes is also far from tight.

Thanks for your help man, not just today, you've been a terrific source of information over the last 5 years.