On the constant speed version of the AT engine, either Woodward UA or UG governors can be used.The UA/UG Woodward Electronic Actuators are electro-mechanical actuators capable of isochronous operation. The actuators, which are mounted on the top left side of the engine block at the rear, are the mechanical device that physically move the carburetor butterfly valves. The amount the valves are moved corresponds to the voltage output transmitted by the Speed ControlThese actuators are designed to operate with Woodward 2301A, 400, 43037, 500 and 700 type controls.