Which assembly plant was it built? My 68 GTX was made @ St. Louis around the end of May, and didn't have the OK stamp. Did have some grease pencil marks around and about, including an unusual (never seen it) mark next to the hood bumper that resembled either an "A" or a star. Also, I am interested in knowing if the driver side valve cover on yours had any marks, as mine had so much grime on it from the PS pump misting it over the years that I inadvertantly removed all the paint when I tried(carefully) to clean it. Any markings that was there originally were lost. Let me know.