Its not something i would just replace.
The rear compliance bush should have slight movement up and down on the rubber, no excessive movement. side to side or in and out, fully inspect the bush for cracks or splitting around where the rubber joins the metal, minor perishing of the rubber doesn't mean they need replacing unless its excessive or causes excessive play, the front bush is very similar, using a bar, check for excessive movement in and out
Check the lower ball joint for any play, and condition of the rubber boot (dust cap).
Also inspect the anti foll bar bushes while your in there, again, slight splitting of rubber is not a failure or necessary an issue as long as there is not excessive up and down play.
