Thanks for the input.  Glad I left it alone.

That's the location of a locating dowel. Leave it alone. No oil would come from there.

Your likely sources of oil leaks are the output shaft seals at your inner cv joints, the rod change seal where the shifter enters the transmission, the timing cover pulley seal (requires the timing cover to be removed to replace it) and the main seal (often called the orange seal) but that requires the flywheel to be removed.

Oh, and the valve cover gasket. Those leak and run down the motor and make you think the leak is from someplace else

I pulled the front subframe/engine to investigate a mystery oil leak.  With a better view of the back of the engine, I notice one of the connections between the engine and the transmission seems to be missing a bolt.  Although I can feel a hole underneath (where a bolt might go through) I cannot get through the holes with a punch or screwdriver because there is a plug or the remainder of a bolt in there.  

Is this "plug" proper, or should I drill it out and put a proper bolt through it?  There is definitely a nut/bolt connection at the corresponding spot at the other end of the rear engine/transmission line.



https://imgur.com/a/v4cJ3Ja