Railbox Cars/ Floor?

I have a few of the Athearn Railbox 50’ Boxcars and am planning to display at least a few with the doors open. What kind of floor did these cars use? Wood, Steel? I’d like to accurately paint the floor. Thanks.

Railbox cars have nailable steel floors. When new, the floors are painted the same color as the interior walls, usually a beige or gray, but the paint rapidly wears off and the floor becomes a polished dark rust color, from the pushing of pallets and spinning of forklift wheels.