I think the old saying people have had around here is that the back corner on the drivers side is where the shorter 'back corner' bolt is said to bottom out...and be a bit leaky back there. So they cut a few threads off that bolt (like you stated above). I never bothered with this and installed all the headbolts as recommended in the overhaul manual. I've yet to have a single issue in regards to this talk over the past 7-8 years the car has been running.

I contributed to the Wiki.