Mine (L48) 1969 Pacer were rusted and they (Lower) & (Upper adapter) fell off & I drove right over them, Thank goodness the Tube held in place at the air cleaner snorkel connection.
I bought GM replacements in 1990 and they were Natural or zinc plated, definitely not black, however I am not sure what the Factory finish was, my originals were VERY rusty and the area around the rivets deteriorated to point of failure. We might need to look at Vintage photos and road tests to determine factory finish.