Hmmm...ok. I could have sworn that it was just the heads and not the block. There was a pic in the mag of a guy holding a mirror behind the engine and it showed LS6 on the back of the head. But, hey...could have also been a bad picture. That could have actually been a pic of just that...an engine head w/ LS6???...and should have been a pic of the block w/ that^serial #.
I tried looking on the back of my block a while back and couldn't see any #'s. I'm going to have to take another look as I'm pretty darn curious. Thanks for the corrections. I know what I quoted in Wiki said the block, but I was certain is was the heads. Oh well...