Nocturn... Correct. It's just the blocks though. That's all. The casting is different. I need to dig up specifics once I get home. All the internals are still the same as the LS1. Same with the heads, cam, bearings, etc.... There is nothing that would make a LS6 block'd LS1 (confusing huh?) any more powerful. It's just more likely to take more abuse.