As far as I've seen, all Bolers and Scamps have a dropped center floor. Some early units did not have the dropped-floor center compartment under the front gaucho for porta-potty storage. That might be what you were hearing.
I take it you are looking for a vintage 13' project shell with a completely flat floor...
I think it likely that something out there might fit the bill, but I don't know off-hand what it is. Hunter? Cadet