Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
I'm not familiar enough with the 400 engine to say that it's normal just from that picture, you need another to compare as Julie says.But my read of it is that it's the manufacturing process that needs to go through there to connect an internal gallery to the filter output route into the engine. Looks like they've machined then plugged it to get in there that way. If left open, it would just allow the oil to bypass the filter route on it way to the internal galleries.