I just went through the same deal with my 1008. I used a center punch to mark center. I used a Firestorm cordless drill and a 1/8 inch Hitachi bit from lowes. The bolt kept catching and finally bottomed out in the hole allowing me to finish drilling a decent hole. I then used an extractor and was able to remove the broken bolt by hand. I also bought new bolts from GM and the bracket for less than $10. Cheap insurance I think.
Good luck,
Jody
Good luck,
Jody