The McCormick 3647665M91 is a genuine Power Take-Off (PTO) shaft designed for a wide range of agricultural tractors, including specific models from McCormick, Massey Ferguson, and Landini. This critical driveline component ensures efficient power transfer from the tractor's engine to implements. Key technical specifications include a total length of 400mm, 6 splines, and a shaft diameter of 35mm. It is also cross-referenced with earlier OEM part number revisions from 3647665M1 to 3647665M9.