I'm interested in purchasing a mercedes diesel and am wondering if anyone can give me some advice on what to look for (and look out for) in a used mercedes.

I am considering 300D and 140D models, as well as the wagon, somewhere between 1983 and 1989.

1. What is the best engine in terms of reliability and repair costs?

2. Are there any chassis related issues to consider?

3. How do I judge mileage in a diesel engine? (what is considered high mileage?)

4. Is there anything in particular that I should be avoiding or watching out for?

Thanks for your help. I'm looking forward to being a diesel owner soon!