what about the bolts there is holding the bracket, caliper slide too the spindle was they phosphate and oil coating
and was all the bolts too all the suspension and drivetrain also phosphate and oil coating
Don't know if they were P & O but focus rather on the look rather than how they got there. Believe they were hardened bolts so somewhat darker than steel. Some will used gun bluing and work them from there to get the look while others will phosphate, tumble then oil
Just what I've done successfully