A power unit includes a rectangular frame base having a left shoe and a right shoe having a longitudinal track on their inner sides, a forward end having a support plate for receiving a jack stand, and a rearward end having a rear plate with an aperture for receiving an actuator shaft. A screw-threaded actuator shaft has a distal portion, and a proximal end extending through the aperture of the rear plate. A lateral screw axel has a threaded aperture receiving the distal end of the actuator shaft, and has its ends extending into the respective left and right track of the shoes. Two parallel lift arms have forward ends, and have rearward ends pivotally attached to the lateral axel. Two parallel connecting arms have forward ends pivotally attached to the forward ends of the shoes, and have rearward ends pivotally attached on the lift arms. Leveling pads are pivotally attached to the forward ends of the lift arms. An automatic-slide-forward-lift bridge is adapted to traverse along the lift arms, whereby the power unit is alternatively operable as a load lifting jack.