Hi, JC:
I understand pretty well why you want to swap to air suspension. This things look terrific but the drive is miserable.
Why do you want to add torque rods and leave a couple of leaves for lateral control of the differentials? IMHO, if you want to put air as the suspension system for the truck, then get rid of the leaves and install a nice panhard rod.
The original links are more than capable of holding the differentials in place while moving up and down, and the panhard provides smooth lateral control of the movement following its arc.
Moreover, eliminating the leaves makes the differentials independent one from the other, making the ride even smoother, especially when offroading.
Just a thought.
Good luck with your project.
Pairoa