I've got an old XT 6SP hub (circa 1989...) on my commuter that I'd like to re-gear. anyone got something like an 11-24 or 12-28 config that they're looing to part with, or can someone point me to how I can go about acquiring the right bits and pieces that I'd need to pull this off? (I do have a freewheel puller tool, so please pardon the pun).