As far as silver vs black on the bottom I am guessing the late '69s got black on the bottom because the '70 340 Darts and Dusters I believe those were always black on the bottom.
25 or so years back I bought a good used bezel and sent it out for professional chrome and paint. Back then reproduction bezels were not available. I know my guage centers are supposed to be black maybe one day I'll do something about that.
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