"In one deposition, Mr. Cooper confronted Raymond DeGiorgio, the head switch engineer on the Cobalt, with the differences between the original switch and the replacement. While Mr. DeGiorgio said he saw the differences, he could not explain why the part had been changed without a corresponding change in its identification number."

Since the part was changed on the later models (post '06-'07) without changing the part number, that means there is no way to tell the new ones from the old defective ones. This goes against commonsense, why was this done?