Bob,
I don't need to add new back-up lights to my 66 K Fastback as they will interfere with the existing back-up lights in the car. I was addressing the question of the oversized grommet on reproduction back-up assemblies (2nd reply, 3rd post of this subject) and the size of the factory original holes in the original question. My "not-so-concourse" solution was to enlarge the existing 1/2 inch factory hole using a GreenLee punch (all other brands are inferior) but, as I don't need to do the "solution", and don't know the size of the repro grommet's required hole, the selection from my more than a dozen punches is academic.
Jim