One thing to remember is the financial crisis that began late 2007 or so.
Prevost and some of the converters "stocked up" on pre-2007 emission engines/shells. When the bottom fell out and financing dried up, some of those units were either not built, not completed, or sat on sellers lots for a long time. Layoffs were going big time and suppliers were not being paid. Some were experiencing parts shortages and just a general difficult time.
Many conversions are built the year before the "model year". Just like cars that you can buy a 2021 in 2020, our 2006 was built and sold in the early part of 2005. My point is that you need to pay attention to more than the converter model year.
It sounds like your are looking for a bus in the "sweet spot" - before emission issues and before the financial meltdown. In my opinion, a very good move.
Les Stallings
Crossville TN
2006 Country Coach XLII