Not sure if someone who wasn't familiar with this device would think it was a piece of coal with a partially rounded-off bolt threaded into it-- If they did that would be a good guess.
I know O2 sensors can be a pain in the ass to remove; the upstream was about a 5 out of 10, but this downstream-- I'm going full 8 out of 10, with 9 being failure with recovery, and 10 being failure and you just throw stuff and go home... Once again, there have been struggles and this was another one. We just snuck this out before it was rounded off; I really thought we were gonna fail on this one. MAPP gas, hammer taps, and it finally broke loose. Had to go slow to make sure we didn't pull the threads out, but it came out. Extra suckage was around the wiring up behind the head, as you have to take the plastics off of the top of the enging compartment out, again... Once again, the positive is that we're getting really good at pulling that stuff off, but it's still a pain each time you have to do it.