As a matter of interest, notice the rubber grommets in the illustrations below. These are originally three different part numbers with different flange shapes depending on configuration of the mating sheet metal panel in the specific location.

      AHH5163   Grommet for outer stud   [front]
      AHH5164   Grommet for inner stud   [front]
        130383     Grommet (rubber) for bracket   [rear]

In recent years the common parts vendors have been supplying one part number only that is intended to work for all three applications. It is a bit of a compromise with a single fixed angle for the flange, and it appears to be longer than necessary. I suppose the intention is to trim the grommet to length depending on how the bumpers fit up to the car body after restoration work, and then squeeze it a little in assembly to make the flange conform to the painted body panel. So far there is no expectation that anyone will ever reproduce the correct original parts.