I took both rear calipers off my 2ws tx5, and put them on my 4ws mx6. It all bolted up right and everything worked fine. I dont see why you couldn't bolt the 4ws calipers into your 2ws car. Only one way to find out.
holy bump batman...
So...2ws to 4ws rear calipers are OK
4ws to 2ws rear calipers need mods to fit correctly...???
2008 Legacy GT Spec.B - Quartz Silver Metallic | Not Stock