Dissociation and doubly differential cross sections are calculated for N+N-2 at near-threshold collision energies using a semiclassical wave packet method in which the vibrational motion of the molecule is treated quantum mechanically and the rotational and translational motions are treated classically. A three-bodied London-Eyring-Polanyi-Sato potential energy surface is used and results compared to those obtained using a purely repulsive power law potential. For a comparison of results, cross sections are also calculated using pure classical mechanics.