[Sam Oliver]

Yes, My guess is the original builder just "missed" that difference when they were laying out holes.   And as I reminisce on my basic introduction to physics as I struggled through my basic education many moons ago, I would think the force working on that particular  forward portion of the mount would be predominantly much less than the force on the rear mount.  More appropriate is good.  But appropriate enough is the final  straw.  Using the Good, better, best analogy, and thumbing through my AC 43 library, I have concluded that it is not a safety issue and will use that ballast mount tube as previously drilled on my project.
  As always, thanks for the input.
Sam