Loosen the rear wheel lug nuts and raise the rear of the vehicle, supporting it securely on jackstands while blocking the front wheels to prevent rolling. Remove the rear wheels, then support the rear axle with a floor jack. For pick-up models, remove the shock absorber upper mounting bolt from the frame, followed by the lower mounting bolt from the spring seat, and then take out the shock absorber. For 4Runner models, support the rear axle with a floor jack, disconnect the lower end of the shock absorber from the axle, and then remove the upper mounting nut to detach the upper end of the shock from the frame, turning the shock instead of the nut due to limited space. After removing the shock absorber, installation is the reverse of removal, ensuring that the cushions and retainers are installed in the correct sequence and that the upper nut and lower bolt are tightened to the specified torque.