As far as I know, the non-tilt wheels also have springs, although the two are different. Attached picture (for which you'll need to zoom in) , while not the best, is of my original non-tilt column, in which the spring appears to be there, just as the MPC's note that it should be. Of course, unfortunately, I can't give you a better picture or dimensions, since you know where it resides.
I think the problem is the wording in the Assembly Manual. Where it notes "For Dual Action Tilt Only", with the triangle symbol for the footnote. As I read this after several times, it means that the spring is part of the tilt column assembly itself, as opposed to a separate "loose" part that can be put on during assembly of the non-tilt column ; not that a spring is only for the tilt column.
Just a thought.
Bob