A fitting is disclosed that includes a body; a first flow passage extending through the body; and a second flow passage formed in the body to intersect the first flow passage. The first and second flow passages define first and second longitudinal center axes, respectively. In an exemplary embodiment, the fitting forms a portion of a manifold assembly of a frac system. In one aspect, the fitting is formed by a manufacturing process such that the body has a parting plane that is offset from, and parallel to, the first longitudinal center axis. The fitting may have a first varying wall thickness defined between the first flow passage and the external surface; and a second varying wall thickness defined between the second flow passage and the external surface. In another aspect, a curved surface is formed in the body at the intersection between the first and second flow passages.
