[NotSoFast]

FYI, You can extend your range of acceptable years into the 2008 and possibly early 2009 coaches. Mine is a 2008 (1223) and has the 2006 Cat C15 engine which has almost no emissions equipment. As with Autos the model year is usually produced at least late in the previous year so a 2008 made in 2007 could have a 2006 produced engine. Get the serial number of the engine on the coach your looking at and give Caterpillar a call and they will have the entire build sheet and dates on the engine.