Assuming this is an M103 engine, and I believe that it is, Benzmac has said that the timing chain on this engine very rarely, if ever fails. This engine has a ratcheting tensioner which prevents slack even with loss of oil pressure.
All you have to do is ensure that you have a single cam, M103 engine.
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in