Hmmm per this site info:
Rather than mounting to the grille, they sat atop tubular stands which were bolted to the wide grille trim. These stands or posts were painted the same argent color as the trim to help them disappear and again give that floating appearance to the lights.
I have seen other references to Argent as well, most photos I have appear Argent (not that they are verified original or that great to really tell, they just generally look light). And I have seen no reference to a separate part number for the CS grille trims (stock was Argent) or refence to the line masking and painting them a different color. The FAMs make no mention of the CS and any differences (drawing notes as for "all C8ZB") and the MPC lists only one grille part for '68, for both 6 ad 8 no differentiation, only RH/LH 8242/8243 parts...
The existing posts and grille are Argent, and show age and no evidence of a darker color underneath, not that they could not have been replaced at some time in the past 40+ years...
So where's the info for "dark charcoal" coming from? What is the source for this differerence, as everything I've researched makes no reference of this other color?