rdowns welcome to irv2 and the Newmar forum.
When you are talking about crown floor is it the floor in kitchen area or all the floor areas. If its in the kitchen and the floor is rippled there maybe a water leak that has gotten under floor and the floor has sweld and buckeled the floor boards. If the sub floor is not ruined from water a new floor could be placed. A Newmar is a good coach and will stand up to abuse but water can ruin any coach. A 97 could have sealents braking down and allowing water in by furnace openings on side wall or the refrige opening. These can be fixed to elimiate the leaks. The Newmar roofs and slides have never leaked on my three coachs I have owned.
As to the Diesel if it is one it may have a low horse powered engine that may have trouble pulling a car but may have good mileage per gal.
It would be a Ford if its gas which is a good gas engine during that time. You didn't say where you are purchaseing coach dealer or private party.
If you have more to ask please do.