2003 F225 TXRB - Cylinder Head Slug???

[Richiela]

Hello:

On the starboard side on my 2003 F225TXRB 4 stroke engine, on the bottom of the cylinder head is a removal-able plug/slug.

A Allen wrench would be required to remove this plug. Is this a water or oil plug?

I'm asking because I'm looking at alternative ways to install gauges on my engine without the expense of the Command link.

Thanks

[boats.net]

Not sure what gauges you are installing, here is port location.
WaterPort F200_225.pdf