Originally Posted by corey
...Technically the ILMOR engine weighs a bit more due to it's cast iron exhaust manifolds, the block itself if the same so no difference there block to block. The 6.0 liter does weigh more than the 5.7 and likely more than the 03' 6.0 (the 03' was an LQ block, in 07' this was swapped for a full cast LY block).
I think a 2003 would still have the cast iron manifolds as well. I don't think Indmar went aluminum until around 2005 or 2007.