If you're looking at a 2006 coach you need to verify the model year of the chassis. You can have a 2006 house built on a 2005 chassis. 2006 model year for the Ford chassis had some major changes with a higher output engine and a five speed transmission. A 2006 the button on the transmission shift arm will be labeled Tow/Haul. An older coach it will say OD on/off (or something similar).
I have a 2006 chassis and have had no problems worth writing home about. Coach has taken us everywhere east of the Mississippi River we wanted to go with no complaints. Added a Five Star tuner two years ago which made the coach just a bit better. Routine maintenance based on Ford's recommended schedule all performed in the driveway. 65,000 miles and going strong.