James Van Driessche

I am looking at an older RV it is a diesel pusher with 200,000 miles and it is a 1989 model. My question, 1st should I even be looking at this unit being this old. If I would continue looking at this unit what are the things that I need to be looking at it. The only thing that I have been told is make sure there is no leaks in the roof. Any help with this question would be grateful. James Van Driessche