Can Anyone Tell Me What Year....

Well ... going by these links relating to features and frame construction showing that Winnebago, for one, does indeed use complete framing above the floor. I may have been wrong, as perhaps the framing is steel and not aluminum - although I may be confused about their Class A construction materials versus their Class C construction materials. Actually, I prefer steel, but is does weigh more and does rust.

The frame schematic on the left of the first link below is clearly the innards of a typical Winnebago-built Class C ... showing an extensive frame above the floor:

http://www.goitasca.com/products/2014/spirit_spirit_silver/key_features/superstructure/

http://www.goitasca.com/feature_comparison