I have a Woods/Dual 3pt trencher with a hydraulic motor that turns the trencher wheels with the tractor in neutral. This moves both the trencher and tractor at the desired trencher speed. It also has a hydraulic ram that shifts the weight from the rear tractor wheels to the trencher wheels for traction. Ram can lift the tractor off the ground. Hydraulic motor speed can be set to be as slow as you want. This hydro drive trencher up can be effectively used on manual shift or hydro tractors. Chain runs off pto and cutting width is adjustable. These trenchers were original made the Dual company which I think is now owned by Woods. Maybe some body out there knows whether these units are still being made by Woods/Dual.