Welcome to the forum... I hope your time here is productive and that you get all the information and help that you need to better enjoy your RVing experiences....
As for your question, you did not state whether the trailer you're interested in is a "Western Edition" (308BHSWE) or an "Eastern Edition" (308BHS), but it doesn't really matter since both models have a 2" aluminum framed floor, which is "Keystone talk" for a aluminum framed, styrofoam filled, plywood/OSB/LUAN sheathed (top and bottom) "laminated floor"...
You can download the Eastern Edition brochure here:
https://keystone-rv-dealer-app.cdn.p...chure-2019.pdf
The floor construction is located on page 15 in the "construction standards" section.
You can also download the Western Edition brochure at:
https://keystone-rv-dealer-app.cdn.p...chure-2019.pdf
The floor construction info is in a similar chart on the same page number...
This is another one of those instances where you might want to verify EVERYTHING the salesman tells you to make sure all information you're getting is accurate !!!!!
Now, as a note, there is not a "construction cutaway diagram" in the 2019 Keystone brochures, but there is one that you can use to help better visualize the way the trailer is constructed in the 2018 Bullet/Premier brochure. You can download that brochure at:
https://keystone-rv-dealer-app.cdn.p...chure-2018.pdf
The "cutaway diagram" is on page 14 and a similar features chart is on page 15, with the 2" laminated aluminum floor listed as a standard feature...
To my knowledge, Keystone has not used a "true plywood floor" in any trailer line for at least the past 7 or 8 years and probably much further back than that. What they do use on "heavier trailers" is a "Dyna-Span" floor that is 5/8" thick, however it's an "Oriented strand engineered floor" not a "literal plywood floor".