What is the threaded Allen block plug for on the rear horizontal block surface directly below the electronics bracket? Does that have pressurized oil behind it? Also do the electronics bracket studs that go into the rear of the heads go into a dead hole? Reason I ask is that both the Allen plug and one of the studs have a little engine oil on them. Looks like one or both are leaking. Thanks.

Not really sure where your talking about with the Allen plug, but yes this bolt holes that go into the head dead end.

Stud holes are dead ended, allen plug is pressurized, some engines use it for low oil pressure sending unit to the ECM