I'm with Kent on it not being original. The wood on original beds has no bolts thru it other than the outer two boards to the angle strips and the bolts that hold the bed on the frame. Otherwise, all the bolts go through the steel strips and into the cross sills and not through the wood. The plank widths would have been as wide as the distance between the bolts you can see on your picture. By 1946, wartime material restrictions were off, so the salesperson was talking through his hat about the steel in the strips being used for fenders instead. I'm sure that GM would have come up with more economical ways to conserve steel. But it does look decent and somewhat unique.
