The original run of MDD models had 133 FSB (867mhz model only) and 166 for the others.
The easy way to tell a OS 9 booting MDD from a non booting one is the booting board has a slot for the original airport cards, second revision has airport extreme slot.
The easy way to tell a OS 9 booting MDD from a non booting one is the booting board has a slot for the original airport cards, second revision has airport extreme slot.