The auxiliary ash tray came about because of the center air conditioning vent on the dash. When the air conditioning was on high, and the regular ash tray was used, the ashes would get blown out of the ash tray. The solution was to install an ash tray under the dash, and not open the ash tray that was in the dash. Not being a smoker, I used the lower one for toll receipts, and the one in the dash never got opened. My car was a 1964, and I have no idea if this secondary ash tray was used on the 1963. Now doubt that it was an after thought by Chevrolet, so there probably is a technical service bulletin on the secondary ash tray.