I have a few option questions one of the letter codes unknown to the 67 Firebird has to be the tilt steering and Yellowbirds article shown for the 68 option makes me believe that every interior upgrade may have its own letters as well? I have a 68 with Deluxe interior with no chrome dash trim no Deluxe buckles no Deluxe steering wheel these could all be unidentified codes in the 67 as well. Any feedback would be great. Thanks Dan