Water Temp sender 3.7L

[solar7647]

Does anyone know what the thread size is for the water temp sender on the 3.7L Mercruiser is. I need to get a new one for the new gauges, but cant find what the thread size is for hole in the manifold.

I need a type "D" for the new gauge and they come in 1/4, 1/2 and 3/8.

Thanks guys