I bought my W124 300D with just a tick under 240K miles on the clock. It came with a stack of maintenance records and I'm also a first time MB diesel owner
Things that have gone wrong in 3 months / 2K miles of ownership:
- Belts and pulley tensioner
That's it, honestly! The car starts / runs / drives as good as any car I've ever owned (I've lost count). I'm hoping to get over 300K miles without any major engine / tranny work.