Interested in buying a diesel for its longevity. I have seen 2:

95 E300D, 33k mi, asking US$22k, looked on edmunds/blue book for trade in value for around $15k.

98 E320D, 47k mi, asking US$28.5k, looked on edmunds/blue book for trade in value for around $30k.

Concerned with degrading quality of recent MBZ model years but thought newer normally are better both design wise and safety wise.

Question:
1. does TD require more often tune-up/repair than regular diesel one? more costly to repair? last as long?
2. what price do you feel fair for either car?

Thanks!