In order to fit Bell End Concrete Pipe into curved concrete drainage constructs there is a need for an adapter .. an example is circled in the drawing. I really don’t know the details and I don’t need to for purposes of modeling this in O scale. Eccentrically .. I only need to create little stub end versions of Bell End Concrete Pipe .. just the ‘Bell” and enough of the body to fit through the casing. I just made them 8mm .. and figured that would work.