I'm helping a friend restore his Shelby and in the process he got a pair of Ford bumper end brackets (C4ZB-17A869, C4ZB-17A870 or C5ZZ-17A869-B, C5ZZ-17A870-
off e-bay. They came two to a box and one pair was mine, one his, if I "fixed" a couple of minor finish scratches. It turns out the brackets were powder coated and to "fix" the minor scratches required the removal of the powder coat. Good luck. I went to my powder coating Guru and he recomended "Aircraft Paint Remover" by Kleen-Strip. Needless to say, it worked. I got a quart (under $15) and applied the stuff, let sit, scraped, wire brushed, rinsed in water and bingo, most came off. (I'll hit it again tomorrow.) A word of caution - the stuff is toxic and stinks strongly of ammonia - but it works. I don't know the effect on metals other than steel. Oh, in the warning section on the back of the can it says - "DO NOT USE ON AIRCRAFT". Figures.
Jim