The invention is a suspension system, typically for use between a cab and a truck frame, includes a strut module having a strut and an air spring, and a control module, connected to a source of pressurized air, for sensing a distance between the cab and truck frame and selectively pressurizing the air spring in response to changes in that distance. Preferably, the strut is a McPherson-type strut and the air spring encloses at least a portion of the strut to provide a compact assembly and includes a three point connection to the cab and frame to resist relative lateral movement between the cab and frame. The strut also preferably is a magnetorheological-type damper so that the control module can adjust the damping characteristics of the strut to optimize rider comfort.