I don't know how far steel bed go back in GMC but the 39 has an
original,strong steel bed. AND a step bumper made of d-plate
I've had two of these beds the second was a short bed that was perfect!
When I want wood I throw a sheet of ply down.
When I want to keep cargo from shiftin' I tie it down with a rope
straps or chains
Wood beds were cheap and easy