rik 00100

i have a 02 impreza wagon and have small problem with the back suspension abt a month ago the back end when going over the slitest holes or bumps bangs really badly on the passenger side so i replaced the shocker with a second hand unit but it was still the same i have changed the control arm and there is no antiroll bar link on this year of model the qeustion im asking is there is a suporting bar witch go,s accross the middle off the car witch is attached to the diff it has large rubber bushes wen i inspected these you can move the bar and bushes with your hands , is this correct and could it have anythingto do with the hard ride on the back end ?,,,,,,