V12 water rail threads

Figuring out how to plug most of the holes in the water rail hardware of the mid 80s HE engine being rebuilt. .
I am using an aftermarket EFI system so only need a couple of sensors, the heater hosetail and small coolant vent. That would be A, B ( or C), D and F.
Over 20 years ago building the HE engine in the coupe I made a note of threads and bought a lot of dies to make plugs and sensor bodies. The threads are shown also in the 2nd photo but may not be correct. There were a few differences in which bosses on the castings were actually drilled and tapped.
Anybody know for sure what the threads are I would appreciate an update.
Because the PO for this engine being rebuilt did not believe in using coolant inhibitor the threads are not in great shape so difficult to use a thread gauge to get the TPI.


Some of these things changed along the way. For example, in your case the RR manifold has two ports threaded and the front one blanked off. I’m pretty sure some cars had all three ports drilled and tapped, and it involved relocating one of the two you have forward and drilling and tapping one of the rear two for something else.

It’s clearly been too long since I’ve owned one of these cars. I don’t recall your C and D at all.

I looked up photos taken 20 years back when rebuilding the HE for my coupe.
The casting shown below has an extra tapped hole at “X”.
The pre HE had the boss next to “X” also drilled and tapped.
Looks like it will be trial and error to some extent to get all the threads identified.