All 69 Tail light bezels had the inner area painted with a silver grey during early production and a darker grey on late production (the one in your picture is a late production unit). This inner paint seemed to peel and fade away faster than the matt black on the outer portion of the bezel. The switchover to the darker color seemed to have happened very late in the model year or maybe even only on replacement parts. I have never seen the darker version like in your picture on a car but I have seen and bought some NOS. The lighter color ones like in my picture is almost identical to krylon dull aluminum which is what I use to refresh them.

Note even the later cars that had the darker colored grilles still all seemed to have had the brighter silver on the tail light bezels.