Simple question that I can't find a definite answer to. Was the rear drum brake backing plate on a 1973 Roadrunner natural metal, phosphate (grey or black), or painted semi-gloss black like the axle housing. I have seen all three answers given. By the rust pattern and lack of any paint residue my inclination would be natural metal (like the drum) but maybe the phosphate metal also rusts pretty evenly. IDK so I am asking. Trying to make as original as possible. Thanks in advance.