The 2004 GTO engine is a ????, LS1, LS2 or LS6? Do the valley cover from it is different somehow to the LS6? The LS6 have a black box under it with open center part, the GTO one has the black box under but with the box with just small openings. What the purpose of those openings?

 

Th 04s had the LS1

 

What about the valley covers? Do them are different, probs. on putting the GTO one on a LS6 block?

 

you talking about the lifter valley?
the ls1 and ls6 ones should be the same, the ls2's are different. they are different because of the location of the knock sensors.

 

The 04 GTO has a LS1 engine (block; 241 casting heads; 197/207 cam), but the intake is a LS6 piece w/ 78mm throttle body.

I'm not sure if the valley cover is different between a LS6 and a LS1 but I don't think they are. LS2 is surely different as Steel Chicken said.

 

What about the diference in the small holes on the black plastic box that the GTO (VC) have on the bottom part, in comparison to the LS6 that have a big opening in the same place? What difference that makes?