Both trims around the 69 tail light lenses are stainless steel.
I replaced the tail light panel on my car circa 1982 because the body metal strips between the lenses were rusted out, but the lens trims are still in great shape to this day which speaks to them being made of stainless steel.
If the inners look bad, somebody may have done stuff like siliconed around them, done a sloppy paint job, blacked them out to sort of mimic a boss look.
Remove the tail lamps, and the trim should polish up great with 0000 steel wool.