I found this thread (as the one on ka-t.org) by searching for something else. Being it showed up in the first google search results, I'm bumping it with a possible answer to help 'the next guy'.
Sorry for being late, but this o-ring is important, and google seems to think a lot of people are searching for answers on this, and not finding them. I took the pic a few years ago to remind myself about it when building my engine.
