OK so I am a little confused. Left tail light should have a clear lens at the bottom for the license plate. Right tail light will not have that lens. Tail light/running light should be the lower socket and Brake light should be the upper socket with the red lens off. You might have two lefts or two rights and turning one upside down will put the sockets in the wrong place. Tail/running lights are "dimmer" than the Brake lights. Wires will be "hot" to tail light left and right, "hot" to left brake and "hot" to right brake light. That is the 4 wires you have. Ground is through the bracket to the bed and a ground to the frame will complete the circuit. Of course this assumes that you have an integrated turn signal stat. I hope this helps

Steve H