Originally Posted by
madpogue
^^^^^^ It's a 1987. There was no "Master" designation in '86. The S likely indicates 19th fortnight, which would be September '86. I don't remember offhand if anyone's come up with a clever name for this colorway.
There's another Ironman thread, "Post your Centurion Ironman....". Would be worth checking in there as well.
I actually found that information shortly after I posted this, I was just coming back to correct my mistake and found your post, thanks for the additional information