"Bushing bind?" Leaf spring bolts/shackles: how tight?

The rear shackle nuts can only tighten down until they bottom out. So over tightening won't damage the bushings, but of course it will stretch the studs and ruin the nuts, so the 30 LB FT is right. And you are also correct in that you make your final torque with the weight of the car on the suspension. You CAN do that with the rear axle housing on jack stands. I know it sure helps "my old butt". lol