Originally Posted by 22GT
Sure- The inner, upper edge should be below the flange on the frame rail, not above it.
looks like you changed the picture. based on what i'm looking at in the picture you linked from someone else's work (and pictures from Aolshove), it appears they may have bridged the gap with a weld. so in reality the torque box someone else installed probably isn't underneath the frame rail the way you claim mine should have been (and incorrectly installed....). i'm guessing you don't have a better picture.
looking at photos posted by Aolshove, it appears the aftermarket convert torque box comes up a little short just as the op describes.
in another picture posted by Aolshove, it appears the original was on top of the frame rail (and not short like the aftermarket).
in reality, whether a person welds it on top like original or underneath (or simply bridge the gap with a weld) it probably doesn't matter since you can't see it anyways. at most you would have to push the toe panel/firewall down the thickness of the original torque box in order to attach it to the frame rail if you put it underneath. that gap is in the noise though.