I owned a 2005 Diplomat for 10 years and was one of the best coaches I ever owned. You'll find that the 2003 Diplomat is something that you can work on. There is not a lot of exotic electrical, like in the slides and other moving components. The Roadmaster RR8R chassis is a great chassis and handles well. In the past few years, a group on the Monaco forum developed a set of bars for the rear end that makes the coach ride like it's on rails. I huge improvement on an old design.
The Roadmaster chassis is dead and gone. When the original Monaco went out of business in 2009, they were bought by Navistar who added their motors and then sold off the rights to Allied Group (Fleetwood) a few years later. Allied now owned the Roadmaster chassis rights, which would never be built again. Allied Group called a new product they produced a Monaco, but it was just a rebranded American Coach on a Freightliner chassis. There is no connection between the original Monaco and the current Monaco, other than the name on the side of the coach.
The good news, through all of the sales and bankruptcies, Monaco parts has stayed opened and maintained older coach records.
If you have no issue fixing the bad flooring, you'll find that the coach will be a pleasure to work on as it was made with a lot of quality.
