From Will Simmons- USA
I'm not sure mine is original but it sure looks old enough to be.
A nyway, i hope from the pictures you can decipher my description.
T he skids (long rails) form the botom half of the sides of the box and the bottom board of the box is nailed to the board closest to the engine (i call this the front board) and has a bolt going through the other end to the rear cross piece that the skids sit on. it is not nailed to the back board. The top part of the sides are nailed to the front and back boards of the box and are not attached to the skids. The measurements of the pieces are as follows: bottom board is 9" long by 51/8" wide by 7/8" thick; the front and back boards are 8" long by 5 1/4" wide by 7/8" thick (the bottom board is a bit smaller in width as it has a gap down either side, maybe for drainage); the top part of the sides are 10" long by 5 " wide by 1/2" thick (the skids make up the other 4" of the length of the front and back boards).