Dan.
I have a seat back without the cover. Will get the dimensions and post here later today
Frame is 341/2" long by 173/4" high with a center brace in it. Frame is 7/8" deep by 5/8" wide stock with 16 1/2" long center brace. Bottom of frame is cut at 45 degree angle at the corners. 1/8" Luna for the skin. All corners are blocked with 45 degree blocks. Three hinges at bottom.