Its not the tack welds that support the torsion bars, its the bolt in cross member. the cross member ties the two sides together very nicely. A nice bit of engineering on Mopars part. :burnout:MT
The bolt in part and the arched part work together as an assembly (which is maybe what you are saying), and with the floor. The tack welds tie the floor in with the other 2 parts, both for some strength and for stability.
In this new case, the angled bits transfer force partly to the floor immediately above them and also to the tunnel part and cross member. The floor stabilizes the whole thing in a horizontal plane and does add some strength. The design is actually the same except for the angles. That is why the quality of the welds at the angles are important.