Decisions! Decisions! To pull it all or try pulling just enough? Either way you go with regard to the exhaust studs and their nuts it usually works a little easier when everthing is hot! So get the all your tools ready and your plan of attack then get the engine and manifold up to temperature before you start trying to turn things!

The entire manifold will require 12 chances for some kind of failure, either stripping a nut or breaking off a stud. If you go the partial route you would have to remove each of the four forward studs or the eight rear studs to get the either manifold to slide forward or backward because you can't pull either manifold straight off the studs with the bellows intact. Now you might be able to get the forward nuts off, then destroy the failed bellows, get the manifold section off the studs, then remove these studs. That way you could install the new bellows, get the manifold section in position, and lastly install some new studs, then the nuts to get everything back into position.

To accomplish this you can use whatever rusting or seizing of the manifold nuts to your advantage. And a second jam nut over the original and then use these stacked jammed nuts to turn the manifold studs out. Again this will be easier with the cylinder head up to temp, use the melted wax trick on the manifold studs at the cylinder head edge not on the ends near the nuts. Another trick that could help is with everthing up to temp and then use a can or two of electronic compressed dust-off gas to spray on and cool, therefore shrink the manifold flanges and studs ever so slightly compared to the warm cylinder head.

If worse comes to worse you can always remove everthing and get it done! I have a very well worth it, $20 set of cobalt left-hand drills and fluted extractors that I've used successfully to remove a couple broken studs that did not have enough meat left to grab with vice grips. If you've got access to welding equiptment using the trick of welding an oversize nut to the remainder of the broken stud is a pretty reliable method also! Good Luck!