They look very similar to the ones I have....

Cheers, Ian

Perhaps it's Just me, but for all that stuff I would just drill it out for a helicoil insert, and be back to a stronger original thread size.

Are you talking about regular left hand bits or are you talking about the stubby left hand bits with extractor splines on them (see picture linked below)?  

Sears sell  a "reverse" drill bit.  Instead of using an easy out you use this drill bit; as it drills through the bolt remains it also works to turn the bolt out of the hole.   Haven't snapped one ...yet

Cheers, Ian

The bolts supplied by our host for these brackets are ridiculously long and rust as you've found, I suggest using 5/8" or 3/4" long bolts.

I recall reading sage advice on this subject from Spank and it works, I've done it.  Assuming you can grind the latest Ez Out (misnomer) out of the way and center a drill bit on your previous drilling, drill it and screw it IN until it falls inside the sill.  The backside of those bolts rust and make for a really iffy extraction.  The trick is to not care that a broken rusty bolt is inside your shell... 

Better to keep grinding the 2nd extractor out, then grind or drill the bolt out using a drill that fits into one of the other unharmed holes. What should remain is just the threads of the old bolt sitting in the threads of the hole. Then slowly and carefully clean the treads with a tap of the right size and thread. If you do mess it up you can drill and tap for the next size up as Doug Lawson suggests. Using anything smaller than the original size is asking for trouble and hurt. All the bolts are designed to hold the original bracket in place. You are adding an after-market adjustable bracket, that may need more holding power than the stock one. If your undersized bolt breaks or pulls out, that would leave the remaining bolts holding more stress than intended. Your alignment may suddenly fail, jamming the tire and spinning you around faster than you can say... anything.
Besides, a smaller, self-tapping screw will just break like the extractors.

Well, I found a grinding stone dremel tool bit that was actually able to grind away the extractor fairly easily.  Feeling elated, I even took a picture of the drilled out bolt.  Now, having most of the bolt drilled away, I figured it should come out fairly easily.  So I found what I thought was a much stronger looking extractor and slowly and carefully tried to screw out the remainder of the bolt.  You can guess what happened...that stupid extractor broke again in the bolt!!!!  But at least I know what to do now.  I will grind this one away too, but instead of using an extractor, I will try to use a regular screw and back the bolt out the other side instead of trying to pull it out.  If unsuccessful, will just try to drive a self taping screw into the bolt hole and just leave it there as a support.  Should be good enough IMO.

I don't own any EZ-outs.  IMHO they are way too brittle and therefore... risky.

Do you have a die grinder and air compressor?  If you do, get a small carbide flame point or tree point bur and carefully, slowly, cut out the center of the broken extractor and the bolt.  

Once you get it out you have a couple of choices.  My preference is the easy way.  If I remember correctly the bolt you broke is 5/16".  Therefore, once the ez-out is gone, tap the hole out 3/8" and enlarge the corresponding through hole on the bracket.

I was trying to install an adjustable rear camber/toe bracket on my car, and was successful in removing 3 of the four screws that attach the bracket to the subframe.  However, one of the horizontal ones (the one right under the radius arm shaft that attaches from the side) decided to shear off about half way out.  I was surprised since normally if you get it loose enough to turn it will come all the way out but I guess it decided to give out halfway.  Long story short I was able to drill a hole in the bolt and put in what turned out to be a sorry piece of crap extraction bit that snapped off in the bolt!!   I barely put any torque on that piece of garbage (this is the second time it has happened with those things, they are a waste of money).  Now I can't drill it out and decided to give up after wasting a good part of a day.  I figured the three bolts should be sufficient to handle the load that a single bigger one (the radius arm shaft) can deliver, and it being on the rear wheel, should be low risk for safety.  Has anyone gone with three bolts and have had any negative experience?