I suspect a pretty rare ( and rough) piece.
http://cgi.ebay.com/ebaymotors/1975-Buick-Limo-/190917865406?pt=US_Cars_Trucks&hash=item2c73976fbe
http://cgi.ebay.com/ebaymotors/1975-Buick-Limo-/190917865406?pt=US_Cars_Trucks&hash=item2c73976fbe