Okay, I thought I had piston slap, the O-ring issue fixed it. Now that, that's gone, I hear another noise. There's a "clack" noise as if it's one cylinder and you hear it each time it fires. The techs at the dealer say it's normal, but there's a bulletin that says the LS1 makes "abnormal" noise, that could be anything!

Can anyone tell me what it might be so I am better prepared to fight with this?