An actuator control system includes a housing assembly having at least one line therein for controlling operation of an actuator, and a modular controller attached externally to the housing assembly and interconnected to the line. A method of constructing an actuator control system includes the steps of: assembling a modular controller, the modular controller including a control valve therein for controlling operation of an actuator via a hydraulic line; testing the modular controller, including functionally testing the control valve; and then attaching the modular controller to a housing assembly having the line formed therein. Another actuator control system includes a housing assembly having at least one line therein for controlling operation of an actuator, and a modular controller attached separately to the housing assembly and interconnected to the line via a manifold of the modular controller, the manifold including a concave interface surface which receives the housing assembly therein.