Most likely your rear shocks and springs are gone. The rear springs going on XJs is quite a common thing
if your stock bro just use S-10 leafs and a spacer and the front and replace all the shocks and your ride should ride 5x better....
+2. As oddly as it sounds, XJs will have sagging spring issues after time. Shocks, most likely shot. You could do what the first poster reccomended with the S-10 springs, aka "Bastard Packing", but for what an O.E set goes for, thats honestly your best bet.
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