Freeze plugs

This engine has 4 freeze plugs under the exhaust manifold.

I assume you need to replace these because you have a leak. If that is the case, I would suggest you pressure test the system in order to confirm this is where the leak is coming from.

https://www.2carpros.com/articles/radiator-pressure-test

Please see the pictures below. The first is of a 250 (4.1L) and the second is a 230 Chevrolet engine. It only has 3 but it is a much better picture.

Please let me know if you need more info. Thanks