Included is an extra headstock for end door wagons, which had projections on the buffer body tops to retain the floor planks. Floor planks were not generally fixed, and could be removed and replaced once the "curb rail" at the bottom of the sides was taken off.
When buying from this online store you can choose between:
A standard plain planked floor,
A planked floor with bottom doors
A longitudinally planked floor.
The retail pack supplied to shops includes a "planked" floor with bottom doors.