Follow up- start with a 1/4" drill bit and move up to 5/16th's bit, if this happens to you it is fixable. Chevy probably will sell a new stud insert, but punching the old one out from under the car did not seem possible (I tried!) So I drilled it out and replaced with a 1" 10mm bolt with a 13mm flanged head to match the 13mm nut on the bottom that I had in the tool box.
You can drill out the "stud" (similar to a lug nut bolt) and carefully hold it in place as you thread thread the nut from the bottom side (IOW- contort your hand painfully to reach where ever you need to go!).
Be patient (lots of beer breaks) and lift each side of the suspension to align the end link bolt and all will be good!
Remember- have fun!
