Here are a couple of pictures of my 32 5 window seat frame. It measures 38" x 18" at the bottom and 45" across the top. Bottom and sides are steel with wood across the back.
The very late 31 had the metal frame seat were all the other had wood frames with the side wings were the only metal item on them. The late 31 were Very close to the 32 but were a bit off from the 31 over all it was the same size.