ok, so i put mine on today. WCB....those holes are for the wires to come down so you can wire them up. There's actually no real trick to putting them in. I simply drilled up from the botton the holes for the wires. Then I put the lights on, made sure they were straight (made sure the holes went across the cab...I found if you hook a tape measure to the bottom of your window sill and then bend it over, it will give you a straight line to use as a guide). Once they were straight, I just used a drill to screw in the screws and presto, they're done...just had to wire them. I would definately drill the holes for the wires first so you know where to position them, then all you have to do is line them up.