Install new body bumpers: Between the frame and the trailing arm is a V-shaped rubber bumper that prevents the rear suspension from bumping the frame. If this item needs replacement (if its cracked or worn), this is a good time to simply remove the old, and replace with new. Its held by a single nut. Install the new trailing-arm assembly: Insert the end of the new trailing arm into the frame channel. Carefully replace the shims on both sides between the trailing arm and the channel while inserting the bolt. Once the bolt is in place, tighten the nut and set the cotter pin.