The disk drive system has rotatably mounted spaced apart magnetic disks, a disk motor for rotating the disks, an actuator hub, a motor for rotating the actuator hub, and a control circuit for controlling the disk motor and the actuator hub motor to permit selective positioning of read/write heads over the disks. The actuator hub has an actuator arm extending radially therefrom. The actuator arm has an open slot located on the perimeter of the actuator arm. A head gimbal assembly for mounting the read/write heads to the actuator arm has a boss located on a proximal end of the head gimbal assembly. The boss registers with the open slot and is sized such that when the boss is swaged while within the open slot an outer surface of the boss expands into an inner surface of the open slot so that the spud and the open slot keep the head gimbal assembly fixedly attached to the actuator arm.