It reads like a core plug(freeze plug) rusted out.
Left side of engine is drivers side, right?
In this article it shows the 3.0l block from both sides: Ford Ranger II 3.0 liter Engines
Drivers side just has the one core hole/plug, in front of oil filter
Passenger sides has two core holes/plugs
If that is the problem then you need to get what's left of the plug out, they just pry out.
Then install a rubber freeze plug, google it.
Engine probably overheated because the plug started to leak and drained the coolant.
But even after you install the rubber plug that may not be the end of it.
"overheated badly" causes head metal to expand, and that can crush the head gasket between head and block, causing it to leak(blown head gasket), expanding metal can even crack ruining the head.
You could do a compression test on the engine now, maybe see if there is another issue that may cause you to pull the heads, making core plug easier to get to