There are many reasons not to just change the timing chain without checking it. The most important is what if the previous owner changed it say 10k ago? Then just a waste of money.
More important is to inspect the chain guide in my opinion. If the chain checks good. There is no really sensible option to getting a proper chain stretch reading. To be accurate you have to make sure that an offset key has not already been installed on the cam. They tell me harbour freight has a dial gauge and magnetic base for about twenty five dollars on sale. Useful for other things as well over the years.

I agree with this. Never change anything you don't know is bad, mercedes parts are just way too expensive.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.