Yes, excluding a broken leaf spring (which is one problem you could have,) the Calmini kit will get your rear suspension looking better. The kit includes add-a-leafs, new shackles, and rear shocks for the back end. Almost the entire rear suspension. This should clear up any problems that you have... or perceive to have.
Edited to add: If you could get some pictures, they may help us determine if there looks to be a "problem" or not.
-Jeremy
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"I'd like to move us right to Peter Gibbons. We had a chance to meet this young man, and boy that's just a straight shooter with upper management written all over him." - Bob Slydell (Office Space)