Welcome to iRV2.
The introduction of different models and differences in chassis production dates verses final production dates ; can be problematic... to say the least .
Usually model year designation doesn't take place till September of the year ( so 09/06 would be sold as a 2007 model) and any bare chassis in the manufacturers yard would be built as 2007. Personally I don't think a manufacturer would have chassis sitting for a full year , 3 or 4 months maybe.
The model name may have been introduced as a prototype ; a late season change in production meant to be a lead in for the coming year , but some times due to limited demand , or problems with the name itself , the model designation disappears .
If you have access to the 2007 brochures , can you see if the floor plan; of the 2006; shows up under a different name plate, where the floor plan wasn't available in 2006.
Good Luck , hope you get this issue sorted out.