Very helpful, Steve. You are assuming that somewow I get the bolt to turn. What if I cannot?
How badly am I screwed if the head snaps off?

If a breaker bar and pipe extension don't do the trick, that leaves me with the cutting torch alternative that you suggested. Is it a viable option for me to apply heat on the bolt head, the bolt thread end, and/or the carrier to try to break the bolt free from the internal rust inside the carrier? Or does experience reveal that this never works? Would this surely damage the lower end of the kingpin or any of the items in no. 58 on your diagram, especially item 41?

If no bolt turn or if its head snaps off, is a Sawzall a viable option instead of a cutting torch? Again, thanks for putting me in the right direction.

__________________
Douglas
1959 M-B 220S cabriolet