Exhaust manifold bolts are a but different from water pump bolts. They are smaller 5/16" diameter. Most go through a fairly thine ear on that manifold. Nothing much for it to seize to except the head. Several of the 3/8" water pump bolts go through the timing cover before entering the block so if they are seized they can be seized to that also.
The one close picture we have doesn't really show what this broken bolt goes through but with the approx' 3 threads showing it may be directly into the block and not through a timing cover.
All I know for sure, If I already had the engine on a stand with ample access to it, I would have had my drills and a tap out days ago.
If you watch Youtube you would find "side by size comparison" of products that claim (certainly appear so) to work much better than PB Blaster. But then again, at home I could be well past the issue before such a product arrived in my mailbox.
You have to understand that I worked in plant maintenance of a textile mill for 10 years. We dealt with this sort of thing at least once per week. The "fixers" in weave room, spinning room, etc,,, had only a prescribed group of tools required to make the typical adjustments and/or repairs on those particular machines. If/when they broke a bolt, a workorder was delivered to the machine shop.
After dragging a toolbox across the plant to where needed, "I'm going to go smoke while you bolt the part back in place so it provides a center guide to that bolt". The look on their face was sometimes priceless. LOL They truth was, I'll be placing as much as 100 feet of drop cord from the nearest outlet. More or less as much air hose too if its need is expected. Only chemicals we had was a spray solvent labeled 711 and a can of rapid tap. In majority of cases a spark or flame was not allowed. Too much adjacent grease and fibers to ignite.
If/when a side grinder was required, a second man with fire extinguisher in hand was required at stand by.
Remember that old saying, "Keep on sucin' 'till you succeeds"
