The Ls1 fully dressed and prepped for a manual is 497lbs per GM, 45x prepped for an automatic, and the LS7 was more because of the dry sump (but the engine was around 450-470)
The Ls1 is heavier, the Ls3 lighter. When prepped for a manual + transmission it's under 600lbs.
http://ls1tech.com/forums/generation...ls7-crate.html