Torque Box Question

In theory what you say makes sense. It might however have to do with cost vs strength. What the factory did may have been "good enough" a s far as the engineers were concerned. Maybe it had to do with how everything fit in the assembly line jigs when being built. Remember, these things were built in a hurry. Look at production figures of just US built A bodies for only 1968. It averages several cars per minute 24 hours a day 7 days a week. Maybe it was more rigid the way they did it. Maybe it had to do with assembly line access to feed the parking brake cable through. Maybe how the pieces fit in the assembly line jig, maybe the added complexity of adding the extra spot welds to the trans crossmember, or all of the above. We werent there, we dont know, but all of the above are plausible explanations. Honestly, I'd go with the "cheap route" in labor, and material cost vs strengtb.