Hey guys, i have a grand national (I hope) 1987. How can I tell if it a genuine GN? The rear deck lid has been replaced and has no option sticker on it. It is all black and looks just like a GN on the outside, it has the correct interior seats and all. It does not have a grand national dash plaque! Just says BUICK on it. Is this a red flag?? Also, if I find that is in fact a GN, how could i go about getting a replacement option sticker for the trunk?