2004 clk55 v8 mystery hole next to intake manifold gasket end

[forgetful me]

removed intake manifold for vacuum leak-when reinstall noticed a 2in. square opening where front edge of the intake manifold gasket ends. did not pay attention when removing-dose it have a gasket or cover, where it goes into the head or block? squirt some ATF and it disappeared-is it a vent hole ordid I lost a cover? please help.

[nulu]

You didnt loose anything its not used ,at drivers side head front right ? just orientate right and left intake gaskets on correct side good to go

[forgetful me]

Thanks-Nulu for your expertise.I think you know what I am referring to. It is the extra [ driver side head] opening slightly behind the oil filter housing-is it an empty void, should it have a cover to stop things or water going in that hole. do I need to worry about the ATF I squirted-I saw no mounting bolt hole on the surface like the other side 's EGR. I looked thru whole garage and did not find any extra part. I think it is same forE320.