Model dependence of unitary isobar model treatments of NN-->NN pi at intermediate energies

We compare two ''conventional'' relativistic unitary isobar models for the NN..-->..NN..pi.. reaction. One model, which preserves two- and three-body unitarity, contains only pion exchange, while the other, based on a two-body coupled-channels approach, includes heavier meson exchanges. Thus, we attempt to identify the model dependence of predictions for the NN..-->..NN..pi.. process over a large part of final state phase space. Differential cross sections and a variety of spin observables are examined. Implications for the identification of exotic dibaryon resonances are briefly discussed.