Abstract: The problem of reducing the number of parts and reducing the manufacturing costs of actuator arms in a power driven actuator system of a type including a planetary gear train (42), is solved by providing an elongate torque shaft (40) coupled to the gear train. A pair of ring gears (56a, 56b) are spaced longitudinally of the torque shaft (40) as part of the planetary gear train (42). Each ring gear (56a, 56b) has identical actuator arm mounting portions (64) facing in opposite axial directions of the torque shaft (40). A pair of asymmetrical actuator arms (16) project radially outwardly of the torque shaft. Each actuator arm has identical mounting portions (66) on opposite axial sides thereof complementary to the mounting portions (64) on either ring gear (56a, 56b) for interchangeably mounting either asymmetrical actuator arm on either ring gear to be driven thereby.