the mig welder is the way to repair bolts broken flush with the head. drilling is asking for head damage.

hold a nut over the broken bolt and weld a nut onto the bolt. turn the bolt out with a socket on the welded nut.

if you never what to do this repair again...install headers...oem manifold design is the problem

 

Based on observation of my truck, (cases may vary): The oem manifold is just fine, the problem just looks like the original bolts having been over-torqued. Age is also a factor in my case. It is an '04 (14 years old) with 130,000 miles on it up to when those two bolts broke. That's a good use and not a problem by my standards. Heat and rust eventually gets its way on everything. A liberal coating of the threads in the head and the bolts with Permatex copper anti-seize should ensure them easily removable if/when have to go into it again. (eg motor rebuild at some point)

I have to post a minor disagree comment with the headers suggestion. Don't just jump to that, think it over first. Headers can create new and other problems. Imho if is a regular truck, regular use, daily driver type then just replace the bolts and gaskets, truck on. If you are into mods and upgrades looking to spice your weekend ride for rippen' around scaring women and children in your chicker getter, then sure.

 

That's why this seems to be an ongoing problem with 3rd, and 4th gen trucks....... Folks have spent big money several times to have this condition repaired, new bolts, new manifolds, and still the bolts break. There is more to it than just installation error.

 

i worked at gm when they had the same problem. redesigned manifolds fixed the problem. the manifold problem is more for the 4th gens where the bolts are sheared off by manifold movement. 3rd gens tend to bread at the head of the cap screw rather sheared flush. this is a design problem.