Dimensions are not critical. We used a #9, which I still have, when I was young. I made a swath board from whatever piece of scrap oak wood was around. 5 or 6 inches wide by 20 or so long. Important parts are the flat piece of steelwith holes to mount to the cutter bar and a center hole for the bolt that fastens the board to the cutterbar to go through. You need a heavy spring and assorted washers to fasten the board on. Spring is to let the board flex when turning and when hay is heavy. A piece of flat 3/4 or so wide thin steel along the bottom of the board protects it against wear. The above parts can be fabricated. More critical is a stamped steel bracket to fit a wooden rod in to help fasten the rod to the swath board at an angle, possibly 15-20 degrees. The last rod I made was from an old broken hoe handle with the rounded end still good. The rod is held on by 2 bolts with the factory metal piece having square holes so carriage bolts can be used so as not to catch on the hay. Wooden rod is sawed at an angle so it fits flat against the board and the metal piece fits flat against the board so tha hay dosen't catch behind them. Hope this helps.