The Stovebolt Site Forums The Parking Lot Panels 'N Burbs AD Suburban/Panel rear floor "swapperoo"

This might help.
Stovebolt Techtip
Old 'Burb, New Bed

Another JC Floor Article

The body was assembled around the floor in Single Body Units. i.e. Panel, Suburban, Canopy Express.
Replacing the rear floor in a Single Body Unit is not a easy task.
Panel truck Factory Assembly line.
Photo one
Photo two

Parts catalogs do not show a part number for the Single Body Unit rear floors. Therefore were NS > Not Serviced
Photo A
Photo B