i've had reasonable results hammering out the original two piece hubcaps from the inside, sure they are not perfect, but from 5 feet away or once covered in mud, it's better than it was before. the back side is curved to match the front, only where the letters are placed has a special indentation in the back part, so you can only hammer in the bottom of the letter flats, around the letters is the no-hammer area, but that's a small area.
i'm too worried that if i take them apart i'll never get that nice round edge back, i would like to see someone post how to do that.
i have several chrome Chevrolet and GMC hubcaps for the 3/4 and 1 ton, but most need some work so i'm saving them for when i know better how to proceed. -s