So bad shocks, if shocks do not work right, the springs will constantly be bouncing, and that can cause bad tire wear.
I would replace all 4 shocks with a quality set, inspect the spring bushings for slop, and extreme rubber decay.
There are multiple ratings for rear springs, main thing for you is remembering that 53" spring eye to spring eye measurement is the most likely spring you have, and putting a spring set with a higher rating (more leaves) will result in a rougher ride. I recommend replacing u-bolts, especially if you put in a set of spring with more leaves.
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