A double-ended extendable driveshaft (106) is provided comprising: a first shaft portion (152, 154) that has a proximal end and a distal end； a first shaft coupler (110, 112) fixed to the distal end of the first shaft portion (152, 154)； a first rotary coupler (160, 160', 162) supported for rotation on the proximal end of the first shaft portion (152, 154)； a second shaft portion (152, 154) having a proximal end and a distal end, wherein the proximal end of the second shaft portion (152, 154) is slidingly coupled to the proximal end of the first shaft portion (152, 154)； a second shaft coupler (110, 112) fixed to the distal end of the second shaft portion (152, 154)； a second rotary coupler (160, 160', 162) supported for rotation on the proximal end of the second shaft portion (152, 154)； and an actuator (158) coupled to the first rotary coupler (160, 160', 162) and the second rotary coupler (160, 160', 162) to extend and retract the first shaft portion (152, 154) with respect to the second shaft portion (152, 154).
