I got the clamp from the dealer, but opted to replace all the bolts with M6x1.0 SS allen-head bolts.

 

The casting the broken stud goes into is aluminum, correct? Minimal heat causes a lot of expansion with aluminum, much more than cast iron. I have used a small Blazer-brand torch for similar projects, yes careful is the watch word. Just play a tiny pin-point flame to the surrounding casting area. No melting is necessary. Maybe a minutes worth of heat does wonders. That and prayer.
Keep use posted on your results----what would a dealer do?
Dave

 

dalbrecht, you may have missed page 2. I got it out using a stud extractor. The idea of heat crossed my mind, but it was to be last resort. The stud was very close to the tranny guts and aluminum is so soft you are likely to pull out the threads. PB Blaster and the stud extractor got it out without any collateral damage.

 

HEY FIREMAN,
Congrats to you---------------in my past of 'playing' with aluminum heads, we used to place Heli-Coils into aluminum thread areas and that made future removal so much easier and torque values could also be increased-----------------. I liked your C-clamp idea---------I might have used a Vise-Grip and forgotten the whole mess---------------------???
Dave