The 300SDL would be your best bet...a 300SD from 1984 or 85 would be better. The 5 cylinder diesels are pretty much bullet proof. My "new" one has 175,000 on the clock...the old one had 350,000 before I gave it to my nephew. The maintanence and repairs on gas engines are much higher than a diesel engine.
Old age and treachery will allways overcome youth and skill!