The black plastic seat belts were also available in the deluxe interior the metal deluxe seatbelts was an option, I lost my rear ones during restoration and am having a hard time replacing, deluxe interior also included chrome trim around the windows in 69, worst part is that door panels are very expensive to replace in deluxe.
Jerry Tallman 69 455/4sp Windward Blue, deluxe parchment bench seat, under major restoration je_tallman@yahoo.com