Overview: Quality knows quality, that's why Allison chose Chelsea to join their engineers in developing P.T.O.s specifically for the Allison World Transmissions. The versatile 859 Series is a constant mesh P.T.O. that exceeds the torque capacity of an 8-Bolt P.T.O. while offering the tighter sealing of a 10-Bolt pattern. The 859 Series is an excellent More Info »