I don't know how to explain it any better. I don't know the physics of it, so I cannot put it into better words. If you don't believe the Mopar suspension book and almost every other leaf spring article you can find, I don't really know what else to tell you.
I didn't mean that in any smartass way at all. I don't know how else to put it into words. Other than to say I have tried it several ways and the only way that allows the rear suspension to work without binding is torquing the u bolts to 45 LB FT with the weight on the tires, or jack stands under the rear axle. As long as the weight is on the springs.