You may have been shorted on responses because the Mercedes Board is rampant with Timing Chain Info in the Archives.
At any rate, everyone here has always been good to me, so let me say that the recomended interval is between 100 and 125,000 miles for Timing Chain Replacement.
If you search my Posts you will see that I had mine done on my 560 SL about two weeks ago.
A word to the wise will be sufficient here. They say it is a simple job. It is a simple job if you pay attention and know what you are doing. Alot of things can go wrong with this replacement. Most times everything goes fine.
Please , Please find someone who knows Mercedes and knows your car model before you turn this job over to just anyone. From my experience, I assumed the guy I was dealing with was OK. I am a picky pain in the Butt. Turns out one of his mechanics did the job and something happened. I ended up with a Valve job and I am still trying to find someone to fix some items that are still not right.
Use your head and not your pocketbook on this one and you will be Happy Motoring. If you push it, it could last for a long time. Then again, it could go tomorrow. It is not so much the Chain but the guides that are plastic that wear. The Guides should be replaced and it only makes sense to do the Chain when you are in there.
Get it done right!!!!!!!!!