there are four holes - 2 on the left and 2 on the right- there are "speical" pins that you need to pull them out. YOu can try allen wrenches, those have worked for me in the past. YOu put them in there and push the ends that are in the radio towards the radio and that should release the clips that are holding it in place. The easiest way is to go to wall mart and pick up the pins though, only like $5 or something like that.
