What about brake master cylinder nuts?
Believe your referring to cars with power brakes since manuals don't have nuts used on them or to retain them they may have been dyed but haven't seen that on San Jose cars using Midland pumps. Of course for some it would not patter since them were painted over after the master cylinder was attached to the booster. For others the assembled unit (master, booster, joining hardware, check valve and other pieces) was painted semi-gloss black and two small diameter plugs were inserted, one at each brake fluid port, that left a small round shadow one they were removed and the brake lines attached.
Might, in the weeks to follow start a 69 red dye thread and discussion since I don't want to post those examples here and take this thread sideways
