If we are talking about the 2006 3.5, It actually is a bored out 3.4L The bore goes from 3.62 in (3.4l) to 3.70 in.(3.5l) The Stroke remains the same in both at 3.31 inches. I think in 2007 the 3.5l vvt went to a different bore and stroke. Nonetheless all those 60 degree v6 were based on the same block. the 2.8l back in the 80's.