I believe later service dials didn't use tritium so the "T" would be absent before/after SWISS MADE. Other than that I'm not sure. However, I think mine was re-lumed at some point. Just a hunch because the lume plots have a slight "toothpaste" application look to them.
Whoever re-lumed mine did a good job though because I can only tell from hi-res closeups. Much better than this one:
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