I replaced the rear defogger switch with a nos one I bought.  I had to figure out how to remove it from the housing.

Notice the holes.  Need to get a pick or small screwdriver and press near the top of the hole.  There is a clip that is holding it in and you need to compress the clip to remove.  On a 73 Camaro, there are 3 clips to do this on.  When it comes time to install, simply press the clip back in until it catches.  Also notice the prong with the silver ring – it shows you how to orient things when putting back in.