Fuel sending unit

[soberg19]

I have 1987 seaport with 2 80 gallon tanks. Both fuel gauges don’t work, and my mechanic said the sending units are under the deck and can’t be accessed without cutting into the deck. I thought these me be related to the fuel tanks but am not sure. Does anyone know what these two ports/nuts are for?

 

[alldodge]

Need a reference of where the image is. Is it on top the tank or other location?

 

[soberg19]

This is under the floor in the helm when I pull up the floor. The link has two pictures.

 

[alldodge]

That looks like a transducer for fish finder and depth

Having 2-80 gal tanks, I would expect them to be mounted on each side