I have a 2004 Chevy Impala 3.8, took the upper and lower manifolds off and there are 4 coolant holes around the 6 cylinders , 2 on each side the one on passenger side in the rear was plugged with what reminded me of particle board, i removed it easily, now on the manifold there is just 2 holes both on drivers side one in front and one in back, on the passenger side front there is no hole at all it looks to be aluminum.
On the passenger side rear of the manifold, looks like a hole should be there but is filled with very hard junk like i dug out of the engine but it is not coming out so easily and it doesn't look like there is a water channel there anyway. Are all these holes suppose to be open or is this junk suppose to be in there clogging holes? And how many open holes are in the manifold?
The holes in the 3800 intake gaskets you describe are correct. The other spots that are full of junk is just the fact that the coolant stops there and accumulates. This is normal. Dexcool antifreeze has a tendency to do that, especially if it has never been changed. Just clean the manifold real good before replacing the gaskets and re-assembling the engine.
You may also want to drain the radiator before putting it back together. After it is all done, use a good cooling system cleaning kit from the local parts store to clean out the rest of the system and drain and fill it again.
How Many Bolt Holes In 3800 Intake Gaskets?