We extend some previous results concerning
the relationship between weak stability properties of the geodesic
flow of manifolds without conjugate points and the global geometry
of the manifold. We focus on the study of geodesic flows of
compact manifolds without conjugate points satisfying either the
shadowing property or topological stability, and we prove for
three dimensional manifolds that under these assumptions the
fundamental groups of certain quasi-convex manifolds have the
Preissmann's property. This result generalizes a similar one
obtained for manifolds with bounded asymptote.