Helping my uncle remotely with the freshly rebuilt 392 Hemi in his Chrysler again. He apparently went to put coolant in it, and it started to drip coolant from the oil pan area near the starter. Looking at pictures online, it seems like either an indexing hole or a cleanout area for the coolant passages, but I can't find any references to plugs that are supposed to go there.

Is this a machined hole, and should a core plug be inserted in it? I'm wondering if it had one installed, and is leaking now after being machined.

Any thoughts? It's the hole circled in these two pics. In that second pic it really looks like a core plug. Thanks!