[csx4017]

Rockwell hardness testers are widely available. We don't know the base material or the processes used during fab. It would be academic. I have seen classic fatigue failure surfaces and I am sure there are people in your area that can put the magnifier on it. The bottom photo shows the surface at the failure and my somewhat trained eye sees what could be fatigue, improper heat treatment, contaminates in the forging/casting...Sorry to see since I most likely have the same part. In aerospace the processes were recorded down to the part or at least the batch. I would suspect that these parts did not get a shot peening process either..........As previously voiced " would be great to call LV and find out the details of these critical parts" or at least their supplier??? No drag racing just the twistys !!!