Superbirds, unlike Daytona's had some oddball pieces that were installed in the Metal Shop. Rear window plug, trunk stops, wing support reinforcements, brackets on the trunk floor, jack stud on the trunk floor, and the latch tray bracket.

David Patik's well researched paper suggests these items were installed in "repair holes" which were side-tracks off the main assembly line.

It seems as if they all had to be installed with the regular people on the line. So people had to be assigned extra jobs in addition to their regular jobs for every other car except for this "special". All these had to be done before the car was painted.

So for me, I can see that some cars got the latch tray bracket installed before the numbering machine got to the car to put on the radiator support numbers. Then the numbering machine wouldn't fit. Some cars could have had the numbers put on the radiator support and then someone walked up and put the brackets on, those cars have #'s.

I do not know if it is 50% of the cars, but it is a very high percentage of the cars that have no numbers on the radiator support bracket.