Welcome to the forum. You will find a wealth of information here from knowledgeable resources. I have owned my first Prevost, a 1997 XLV Marathon, since April. I am very pleased with the purchase. Even more so after a trip in June to Vancouver, BC which included a visit to the Marathon factory in Oregon to take the factory tour. As I am sure you know there are several converters from the years you mentioned that are no longer in business. Those coaches are sometimes nicknamed "orphans". Marathon is one of the few that are still operating. One could argue that those still in business were the best managed. On the tour of the Marathon factory they described how they survived the economic down turn by focusing on service, repairs, and renovations during the period they didn't build (read as couldn't sell) any new coaches. They kept their core employees occupied cleaning the floors, painting, and doing building maintenance just to retain the core knowledge and expertise that created Marathon's reputation for quality. Touring the factory and seeing how they design, fabricate, and build coaches was impressive and I now know why my 20 year old coach has no "creaks", "squeaks", "tweaks", or otherwise while rolling down the road. Extra effort like scribing every interior panel to an exact fit, interlocking (think puzzle pieces) the ceiling panels for strength and durability, and the almost OCD level of routing/labeling/dressing/terminating every wire on the coach adds to both initial quality and long-term usability (not to mention ease of maintenance).

If you have any need for service and support of the Marathon conversion there is no doubt that Marathon is in the business of supporting their fleet of coaches. After the public tour, my family was given the new owner tour of the rest of the operation which included learning about (and eventually joining) the Marathon Owners organization and meeting all of the service, maintenance, and technical managers. They keep track of the coaches by coach number. As owner of Coach #450 three or four of the people we met at Marathon remembered building it originally back in 96/97, maintaining it over the years, the previous owner's upgrades, and some unique aspects of my coach (mine was apparently the first built with Independent Front Suspension or IFS from Prevost). We felt like one of the family right away even though we had the least expensive coach on property.

Marathon is considered one of the best conversions and while the value today of Marathons is competitive with other converters that may change in another 10-15 years as some of the older coaches need more TLC and the existence/availability of factory support commands a premium for those converters still in business compared to the "orphaned" conversions. Only time will tell. However, we saw Country Coaches being renovated by Marathon, so they can work on probably any coach. Also keep in mind that I found more Marathon owners and more Marathon related posts on this forum than some of the orphaned coaches.

My search for a coach included the pre-requisite for a Detroit Diesel Series 60 AND Allison 6-speed transmission with IFS being a "plus" but not required. The pre-emissions DD60 is considered to be one of the best power plants ever produced with longevity that should allow it to easily go 750k miles or perhaps 1M miles before an out-of-frame rebuild. A DD60 pushing a coach with a GVWR of 49,800 lbs. is operating at "light duty" compared to the same motor in a tractor trailer pulling up to 80,000 lbs. all day, every day. A friend just had his oil changed at Detroit Diesel on his 2000 DD60 (also in a Marathon) and saw a post-emissions DD60 motor being rebuilt at under 450k miles which seemed contrary to popular opinion of the DD60 series. The Detroit Diesel mechanics stated that the emissions requirements mandated by government regulation cause the motor to run leaner and hotter which reduces lifespan and the corresponding time between rebuilds. The mechanics stated that the "sweet spot" for Detroit Diesels includes the DD60s introduced in Prevosts around mid-1995 until emissions were added in 2002 (IIRC). These years also are known to get the best fuel mileage as well. This may not seem like a big deal but wait until you pull up to the big rig pumps at the local truck stop and put nearly 200 gallons in the tank.

Bus Air was something I was originally interested in owning being a resident of Arizona; however, there are some drawbacks which include losing a full-sized bay of storage and from what I have read a very expensive system to repair and/or replace. When driving my coach with the 30,000 BTU driver's air (comes from dash and driven by the DD60) I get ice cold air (it will freeze the coils at low fan speeds). I can also run (2) of the (3) 15,000 BTU cruise-airs (galley and bedroom) and keep the coach very comfortable even at 115 degrees outside. Starting the generator gives me the salon cruise-air but this is right above the dash-air and not really needed. Parked outside of my home in 115 degree heat while loading or unloading the bus following heat-soak using only the (3) cruise-airs is challenging to keep it comfortable in the heat of the day. I can keep it tolerable (below 85 degrees) but when your cruise-air condensers are located in the front of the bus on the underneath side there is only so much air circulation available particularly when I have the generator running with its radiator ejecting heat in the same zone of the bus underbelly. I don't plan on camping in 115, only driving through it. Bus Air would be the only A/C needed while driving but it will not help when parked in 115 unless the DD60 motor is running; therefore, I am fine with my cruise-airs and dash-air while running down the hot highway. I am not sure roof-airs sitting in 115 would be a lot better but they do have access to more open air (especially if there is a breeze) sitting up high even though they are probably getting heat soaked by the ambient heat and direct sun exposure.

Ask questions, have a qualified person/shop complete a thorough Pre-Purchase Inspection (PPI), and take your time to find the right coach. The purchase of a motor coach includes aspects of buying a luxury home and a luxury car rolled in with an onboard AC electrical generation facility, DC electrical storage with AC conversion, freshwater distribution system, and wastewater storage. These are complex vehicles. Run away from anything that looks like it has been "hacked" by an unqualified DIY'er. Also look for detailed records. I have every owner's manual, every owner-furnished purchase document, and every maintenance record for my 20 year old coach. When you are sitting in your coach the first weekend and you are trying to figure out how something operates, don't underestimate the value of documentation. When watching the TV show Airplane Repo you learn to appreciate the effort they go through to find the logs and documentation because the value of an aircraft is sometimes reduced in half without the logs and documentation. While the value of a coach doesn't seem to be affected by the existence or lack of documentation as a future owner it can make the difference between quickly learning the coach's operations and struggling through a long learning curve.