I had tried to remove exhaust bolts on my 5.9 Cummins to replace gaskets and soaked them in penetrating oil with the first two breaking off. All the bolts on this engine have an exposed center part so I then ran the motor until the manifold was good and warm and put an ice cube on the open part until melted then each bolt came off with no problems.
If you can heat the manifold then cool the bolt somehow it helps greatly in being successful.
The two that broke off were replaced with a slightly larger bolt and nut as there was room to use a nut. Good luck to all. Doug
