The Stovebolt Site Forums The Parking Lot Panels 'N Burbs GM Panel Truck Assembly line Photo, Norwood, Ohio Plant

In 1950 the panel trucks' floors changed to plywood with 5 metal strips over the plywood.

Prior to 1950, panel trucks had 13 boards and twelve strips.

You can tell from the photo that the panels had 5 strips (you can then assume there was plywood under those strips).

47-55 Suburbans had plywood floors.