ihi rhb5 inlet fitting bottom??
 

does anyone know what the size/pitch/ whatever of the BOTTOM half of the rhb5's inlet fitting is?

I'm talking about the part of the inlet fitting that screwins INTO the center section.

I'm gonna take mine off and replace it with an elbow so it will be easier to run lines.

Is it just a metric fitting that can get at NAPA or some AN thing?