Floors were the first to be phased in from plywood to molded fiberglass & that started in the Ocoee Plant in 1984 (85 models) with the Advance models. There may have been a few shipped with wood but they are east to identify by lifting the rear center floors, if they were supported by a gelcoated, molded floor "ledge" its a fiberglass floor, if the center floors sit on a piece of wood screwed to the stringers its a wood floor. Clear Douglass Fir was used for stringers through 1990. I'm not sure what WESMAR did from 1990-95 Although I know they were using a honeycomb plastic board near the end. 1996 Models through 2002 models were 100% composite using various density aircraft foam. The fir used back in the day was far superior to what other builders were using back then and when encapsulated in fiberglass it became very resistant to rot as the resins were brushed into the wood prior to laminating. The Plywood floors, and backer plates such as in the transom however were more susceptable to rot if moisture had a way in. I replace the old plywood floors with laminated high density foam sheets today.