The rear spring shackles (and the front eye brackets) were dip-primed black.
I am currently in the process of detailing the rear under carriage of my '69RS and have just recently removed the gas tank, rear axle, and springs. On my car, the shackles were not painted. I have a reference that states: "rear shackles are semi gloss black......Note: natural (bare) rear shckles are also acceptable" which would concur with the way I found the shackles on my car. See attached pic.
