I am presuming that you are referring to a standard grille.....so here goes. I went by my storeroom today and while I was there I looked at my original 68 grille that is from a '68 Z28, 07C car. The whole inside of the grille is painted silver all the way to the flat areas of the sides, top, and bottom. The rest of the grille is black......and the black covers the entire front of the grille....all the way to the outside edges. The back of the grille has no paint with the exception of overspray. Hope this helps.
Jerry G.