advice & issues to watch for 99 Monaco Diplomat 40 ft pusher

I am assuming getting the model will help me figure out the chassis and engine, but is there any other way. I am not really in any position to be a connoisseur of engines and chassis, but want to stay away from ones that are plagued with issues. I am going at this knowing that I am going to need to put some money in it, but want to know the big items to watch for. What are the difference between the 2 different chassis engine options, does it come down to handling and road manners.