The '60-'61 grille supports have the same grille assembly mounting holes. The '62 & '63 are different from each other and the 4-5-6 are the same for all three years. The grille assembly mounting brackets have the weld nuts attached to them, therefore, if installing a different grille assembly on another year grille support, you only need to redrill holes in the grille support (not the fenders) for proper alignment and securing the grille assembly.
In summary, all the grilles will interchange, somewhat, minus drilling a few additional holes.
TruckNut and RJ, thanks for the kind words.
