Core plug went missing

[HaltCatchFire]

I noticed the temp gauge a little high the other day and checked the coolant level. Sure enough, I couldn't see the level from the cap so I started filling. Then I hear a big ol' splash and my feet feel wet. Pretty sure that hole isn't supposed be there - after some research I figured out it's a missing core plug. So if anyone wants to know, the 30mm ones at NAPA fit fine on a 1610 with a little Permatex #1

Before:


After:

 

[4get gto]

Yea kinda rare they just fall out. Seen them get rusty and rot out.
Just wanting a block heater in that hole I guess..!��