Almost together

[Dead pirate]

Only have one more thing to go on and i don't know what it is. On the side of the head, directly under the thermostat is a threaded hole. Its missing. Any ideas of what it's called. I have to order one20190317_153916.jpeg20190317_153912.jpeg

[Dead pirate]

Found it and put it together. Nevermind

[o1marc]

So what was it ?

[Dead pirate]

Where the radiator (heaters) from the bus flowback into the block. And the radiator overflow