I use graphite loaded wheel bearing grease on my poly bushings, Brush it onto the spring and shackle bolts before installing. Seems to last few years at first then over time the graphite residue builds up and it lasts longer each time. Light see if your rear springs are resting on the overload leaf. If so, that will stiffen the ride a lot. Adding a leaf in back to lift the rest of the leaves off the overload can help to soften the ride. Kind of counter intuitive, but the overload has a spring rate approaching infinity <img src="/forums/images/graemlins/smile.gif" alt="" /> so anything you can do to get off of that leaf will be an improvement.