Well they were/are aftermarket item so there is no correct answer..
However, back in the 60s (esp in the UK) no serious S was without a large Lucas spot mounted to the right of the number plate (see the red car)..... (necessary for reversing rapidly out of the drive when an irate father appeared at the front door
.... or reversing (equally rapidly) back down the wrong lane on the many road rallies that local car clubs used to run..
Today, a small QH reversing light under the rear bumper (see the green cars) is a practical solution that is very effective and much easier to remove than a hole in the boot should you decide not to butcher your original boot lid....
Cheers, Ian (and much cheaper at your local Supercrap than the "proper" item...)