[Killer Bee]

^ good point, relieving thread tension usually works, but I use that as last resort because you may not be able to use many other means afterwards..

something else I forgot to add above.. looks like about three threads showing.. trim a hex coupler down to a thread or two more than showing and thread it over the nipple that's exposed.. braze the the ends of the threads together and back it out..

tack welding a nut or bolt, whichever is applicable, to broken steel fasteners and fittings is quite common..

I still wouldn't pull the head just for that, if you're concerned about other cracks in that area, put a temp pipe plug in the hole after you remove the broken fitting and pressure test the coolant system, inspect for leaks and watch for pressure decay on the gauge..

a lot of varied replies but I guess it's just up to your personal skill level and experience in this type of work.. also depends on what you're equipped with in your shop.. I have all the tools and methods I mentioned above available in my home garage, but that may not be the case for everyone.. and certainly not to belittle your task at hand but that looks like a fairly straight forward extraction.. once you get one or two under your belt, the rest will be a cake walk..

working professionally on heavy junk in harsh climates including sea duty for 30 years, I've had my share of challenges in this area.. so a lot of your options depends on whether you want to be good at doing this yourself or just want it out of there and move on..

good luck!