The buzz words for a search on that series car is M103 and W124 engine and chassis respectively. At the mileage you stated there is the potential for anything on the car to die regardless of defective design or not. You'll love your wagon.
1994 E320 Wagon (Died @ 308,669 miles)
1995 E300 Diesel (194,000)
1999 E300 Turbodiesel (244,000 miles, dies at 255,000)
2006 Toyota Tundra SR5 AC 4X4 (115,000 miles)
2011 Audi A4 Avant (129,000 miles) hate this car!
BMW 330 xi 6 speed manual (100,034 miles)