Drilling my Zbar??
Re: broken bolt boss
If you tack the bolt in for the hole can you still install the bracket with one bolt. You need to have two bolts or you might break the other hole open. If the bell ever comes out of the car build it up with epoxy (jb weld, etc) and drill/tap it. The other option would be attempting to drill the holes deeper and tap about 9/16" or a thread more deep (IIRC the bolts are 9/16")