1997 Ford Explorer the third kight brake

I believe it is cliped in place. And no, the bulb can't be replaced. You can find replacment units for around 80.00 on the internet, or you may want to check out a salvage yard. Keep in mund, there is a balast that runs the light that could be bad. Also, check the fuses. The 3rd brake light has it's own circuit and doesn't run from the same one as the tail lights. Here is a picture of the light assembly. Hopefully you can see the clips that hold it in place.

Let me know if this helps.

joe