I never knew about the V12's , And I worked on the V6's back in the day when GM put V6's in school buses. We even had a GMC wrecker with a V6 to tow buses. Got a ticket on the freeway towing a bus, for going to slow. Lots of torque but no speed.
Fat Teddy that last pic of the black car, well to quote a couple of guys tv show from their family's basement, "Schwing!"
We just did a 305V6 up at the machine shop where I hang out. The thing was huge. So this must be double HUGE!
http://www.stationwagonforums.com/forums/images/smilies/taz.gif ONE THOUSAND EIGHT HUNDRED!!! lbs of GMC monster!! Your engine stand will not hold it!!! I remember the show "Cannonball" On TV had a GMC truck that used one of these engines.
They have a mean sound to them, too. If a 60-66 Chevy/GMC truck is in my future, this would be the engine to get. It might get replaced with a 4.3L if it annoys me finding parts and keeping it running, but at least I could say I owned (or tolerated) one.