The lights in the grille are definitely aftermarket. The '64 Grand Prix had its park/signal lights in the grille just as the ones in the picture show. Some owners of '64 CS Pontiacs replaced their grilles with Grand Prix grilles because they liked the look of the lights in the grille rather than the smaller ones on the Canadian Custom Sport. One could simply add the Grand Prix lights to a factory CS grille since the grilles are the same. In order to install a '64 Grand Prix grille in a '64 CS, one must use the upper and lower panels from a Grand Prix since the Grand Prix panels come with the two sets of holes whereas the CS panels have only the holes for the CS grille. I know this for a fact because I actually have a '64 Grand Prix grille in my '64 CS except I kept my signal/park lights in the bumper and did not use the Grand Prix signal/park lights. The nose of a Grand Prix is identical to the nose of a CS.
-- Edited by Pritch on Saturday 8th of December 2018 10:50:22 AM