Black seat belts are going to be hard to come by. As far as the factory stuff goes 1980 was the last year you could get a black interior in a G-body. Black seat belts were standard issue on the 81-85 models and the color coded belts where a cheap up grade. I've seen a few black belts out there but they were all on the cheap bench seat cars. Those inner buckle sections are bucket seat only. I would think if one spent the money for bucket seats they would have also ordered the color code belts too.