After doing an axle swap on mine I noticed that the A arms were too tight. They would not pivot on the bushing, it was twisting the bushings, and it was acting like the bushing was a "torsilastic" suspension component (Think Cooper Mini suspension and light weight camping trailer axles.). That much tension on that pivot point over time could indeed cause that area to work harden and fail. If you have a shock off check yours and see what you find.
