Hi Dianne,
I don't think they're changing model #'s, it appears the dual model numbers on "specific" Alpine floorplans are related to the OPTIONAL larger residential refrigerator.
On the Keystone website, see the note* (microscopic print) just above the 3535RE/3536RE floorplan... it states:
*SIMILAR FLOORPLAN WITH 18 CU FT. RESIDENTIAL REFRIGERATOR IS AVAILABLE AS 3536RE
That leads me to think that the 3535RE has a 12 cu ft frig, and the 3536RE has a 18 cu ft frig.
As for the carpet vs vinyl in the living area... the website appears to show vinyl, but the current 2015 brochure (printed in May 2014) still shows carpet & doesn't show
the new dual models numbers either.
http://www.keystonerv.com/media/1046...5_brochure.pdf
Your best bet (for correct info/changes) would be to contact Keystone directly, and, if possible, speak to someone in the Alpine Division.
Good luck!
Terri, the Chevy co-pilot