The problem we generally face with the equal thickness bushings is made worse with the polyurathane.
I can't speak to how the Aus Valiants were assembled, but the typical north american based A-bodies using the early strut rods need bushings that when compressed place no rearward pressure on the lower control arm. It's a most noticble problem when using a poly of nylon lower control arm bushing. See here Making A-Body Strut rod Bushings Work
