I have repaired a few like this in previous yrs. The one that is sticking out will be simple if you have a welder. The one with no threads sticking out can be more difficult. At the least, you will need to remove the exhaust manifold, then find a nut that is slightly larger than the stud that's sticking out of the head. Place the nut over the stud and weld in the center of the nut, welding it to the stud. After it cools a little, simply back it out.
Since you have one stud that is broke in the head, you will most likely need to remove the head. It will make it much easier for both studs to be removed. The other stud will have to be drilled out dead center of the stud with a bit about half the size/diameter of the stud. Then insert the appropriate size ease out into the drilled stud. lightly tap on it with a hammer and turn slowly to remove the stud. It's a very tedious job. It may be best to just remove the head and take to a local machine shop where they already have all the necessary tools to properly do the job if your uncomfortable with attempting this on your own. Wish I knew of an easier way, but that's about it to do it right.
