but there's a chance that this change went somewhat unnoticed in house. gm didn't change the part number because of company policy. it actually took an year who does not work for gm digging through junk yards to uncover the change. he discovered it was an extra millimeter of plunger length. he joins us right now to explain and how he discovered it. he's a material engineer in florida. thank you very much for joining us. just to give a quick explanation here, what is the difference between a good and defective switch in this situation? explain the millimeter and other torque ratio we were talking about. >> good morning, chris. based on the information and the work that we did, a 1.6 millimeter difference is what i found to be the difference between the plungers in a new