I was trying to remove the exhaust on my '98 big bear to remove the surface rust and put some high heat paint on it.....when the bottom bolt sheared off while removing the nut. About 1/3 of it broke off.
My question is...can this bolt be removed from the block? Or will this need to be cut off and threaded again?

Here is a picture of the bolt..

 

Well I have tried a reverse thread extractor, vice grips, I have been squirting penetrating oil on it for two days. Any other ideas?

 

Heat the head and stud up nice and hot with a torch. Then wack the stud with a hammer a few times and spray the stud with a liquid like WD40. Attach a vice grip at tight as you can to the stud and sloooooooowly twist it out.

 

^^^ What Doctorturbo said. Try not to heat the stud. You want the aluminum AROUND the stud to expand from heat... not the stud itself. If that doesn't work, drill it out and tap it larger or threadsert it.