Our old motor home was a 1984 Mirage built on a 1983 Toyota chassis. It was titled and plated in the state of Illinois as a 1983 because they go by the chassis VIN number, not the motor home manufacture VIN number. But for resale purposes, it was legitimately advertised as a 1984. I sold it with this explanation.
When we special ordered our 2007 Phoenix Cruiser, I insisted the chassis was also a 2007, just like the model year of the motor home. I never wanted to have that condition again.
Your problem is very common, and very understandable. The motor home manufacture releases their new model year many months sooner than the chassis manufacture. Adding that in slower times, motor home manufactures could have over-stock of previous model year chassis in their yard.
It is very conceivable to have a 2017 motor home built on a 2015 chassis.....a two year difference.
