I cannot tell from either photo whether or not these panels have plywood floors. They both have five metal strips. One photo shows an adhesive or caulking on the passengers edge, the other does not. Since one photo (SUBURBAN) shows a cowl which some (me) believe that there are louvers on the left side making it pre-1951 and the other does not have the cowl, I cannot discern the year. If this was a suburban assembly line, I would be able to see other differences that would help determine the year.

ASSEMBLY PLANT PHOTO #1 - NO COWL

ASSEMBLY PLANT PHOTO #2 - WITH COWL

SUBURBAN ASSEMBLY PLANT PHOTO WITH COWL This one is a 1950 or newer, my guess is 1950.