I found this on
www.camaros.org pertaining to research they were doing regarding the implementation of the woodgrain on the 68 ashtrays: "Woodgrain ashtray. Starting around April of 1968, the ashtray front was changed from black to woodgrain when the surrounding molding was woodgrain (Z87, Z23, or D55)." My March built car has a black ashtray. I hope this helps.