Trivia on stud removal
 

i use left handed drill bits, ive heard you can use a welder no matter how deep it is and build up the weld lil by little but havent tried that.

X2

measure the length of the broken stud, cut the new one to the same length, apply silly putty liberaly, drink more beer.

you could try melting candle's and dripping its waz into and around the cracked bolt

Actually I was shown this on our 2005 Dodge diesel truck. The manifold studs sheared from the manifold shrinking. Machinist for HTA came to our shop. He tig welded a bubble onto the stud. Set a nut on it . Tig welded the nut to the bubble cooled the nut quickly with a air hose and turned them out with his fingers . I tried this on other broken bolts and studs in cast iron and aluminum. I have not broke out the drill since. If you can't get to it with a drill. This is the way. I've been doing it the hard way for many years.

I also heard there is a special arc-welding rod for this purpose. Its made to build high so you can weld a nut onto it. I hear they run about $10 each. Cheap when you really need one.