If the intake is mounted on an engine, the best way to determine whether you are looking at an LS6-style intake is by looking between the valley plate and the bottom of the intake. The intake with the “wing”-shaped floor on the top is an LS1 intake, the intake with the flat floor on the bottom is an LS6 intake. As a tip, all 2001 and later LS-engines came with the LS6- style intake.