Not if your tractor has live or independent PTO as nearly all modern tractors do have. ORCs are needed on tractors with the once common transmission-driven, sometimes called ground-driven or non-live PTO, in order to prevent the inertia of the spinning assembly from continuing to drive the tractor after the operator disengaged the clutch.
I went ahead and hooked up the brush hog without O.R. Coupler and seems to work fine except the hog driveshaft won't stay on. There's no pin hole in Kubota PTO shaft like Ford has to keep it in place. Any suggestions?