Thanks for the quick reply Brad. It came off a straight gassed MS-460. I was under the impression that the D port cylinders were only on 046s? Perhaps this was an early 460. Anyhow, it seems to have cleaned up really well, but i still see "score" marks, although theres nothing i could even remotely snag a fingernail on. Is there a way to clean it up better than this? Muriatic isn't removing anything at this point, but i know this cylinder is worth saving.