A few subtle differences Ive noticed between 63 and 64. Grill, rear end, etc. Is there anything on either of them that would NOT easily be interchangeable? Are the floor pans different since the 64 would have had the optional 4 speed? Mine is a 63 apparently but has lots of 64 items on it leading me to have LOTS of questions. Was looking for identifiers that could not easily be unbolted and moved between cars.