161 mm on the left 168 mm on the right!
A poster on Max-zuk said:
Left side - 161 mm (6.35")
Right side - 166.68 mm (6.5625")...I went 167 mm and was perfect. I'm sure 1 mm either way won't matter too much. Just trying to line the ruler up will have a 1 mm fudge factor from person to person anyway.
Also, I went 1 bit size smaller for the nub hole than what Paul said. It was a snug fit, but worked fine. For others, I would go with what Paul said though.
PS A hole punch is a must for drilling the nub hole.