Bolt at the block is missing, and haven't figured out.
Google AI says 1/2" - 13, but no.
The power steering Bolt on front of water pump is that size.
Definitely seems 1/2", but finer thread.
Could be 1/2" - 14 npt, but that is pipe thread?
1/2" - 20? Seems to fine, but clearly I don't know...