Sorry I didn't reply earlier, was out of town. Anyway, I bought this special Snap-On pipe wrench pliers that SF2skip recommended, and I'll try it this weekend!

BTW, I already tried Xviper's and gfacter's suggestions earlier. Also tried xviper's socket on an impact wrench (hammer type) and hammered as hard as I could under the car till I thought I might break the diff.... no budge. Maybe the excess heating and cooling from racing caused them to freeze more.

 

When I did mine, I used a dremel and cut into the head of the bolt,just about half way, and then used locking pliers to twist them off. Worked perfect and was not too hard to do.
Good luck.

 

If you can get a drill bit on the head of the bolt, you can drill the head off rather than cutting it off. Use a drill bit just a tad larger than the diameter of the bolt. Drill down into the center of the head and the head will come off on the bit. This might be faster than cutting if you have a drill and don't have a power tool to cut with.

I honestly can't remember if there was room for a drill or not; I got all of mine out without stripping any. Just lucky, I guess.

 

I have a set of these from Sears and they did the job without a problem.

Sears

 

I got the first one loose tonight with that Snap On pipe pliers!!! (thanks to S2Kskip! http://buy1.snapon.com/catalog/item.asp?P6...ore&dir=catalog ). Wasn't easy and I still have five to go, but I expect the rest will go easier using this tool from the start as Skip recommends.

Thanks for all the suggestions everyone.