If they are the large lights that go over the vents found in 72s 73s and I'm not sure what other years, you can also get those seitches at Inland RV or Vintage Trailer Supply. The knobs on the other hand are not readily available other than salvage, but you can get a knob that will work from an electronics supply store
Sail on silver girl. Sail on by. Your time has come to shine.