Vintage Moline Plow Co M81 Pitman Wrench. This wrench has M81 stamped in it, there are no other markings on it. The wrench was used by Moline Plow Co and Minnesota Malleable Iron CO, the later was bought by Moline Plow Co to form Minneapolis Moline Co. The wrench measures 5.5 inches long and looks to be in good shape. This wrench can be seen in PT Rathbones Book vol 1 page 333