We present a self-consistent numerical model of light propagation in diode laser arrays. This model has been used to study the free-running modes of a five-element gain-guided array operated just below threshold. The resulting calculations show that, in contrast to index-guided arrays, the modeshapes in general bear little or no resemblance to the "supermodes" obtained previously from linear perturbation theories. In addition, we find more than 5 modes for an 5-element device, so that the intensity maxima in the near-field are not necessarily centered over the stripes. These observations are explainable in terms of a simple plane wave model of the array cavity.