Well, if I tell you it NEVER needs to be replaced, sure as hell next week it'll break on ya!
If it were mine, I'd do it at closer to 200,000, but only if I planned on keeping it for another 50-100,000 miles. I mean, depending on if there are signs it may be stretching or something.
MB doesn't outright recommend replacement as a maintenance item.
There are some concerns on certain engines that MB knows about, like some of the 60 series diesels, but none I am aware of on the 104 motor.
The chain tensioner I know there are various concerns about. Usually you'll hear the chain rattling for a few seconds on cold startup if there is a tensioner problem. If there are no tensioner or chain related problems on the car, I'd leave it all alone, at least for now.