  This paper concerns the class of contractible open 3-manifolds which are
``locally finite strong end sums'' of eventually end-irreducible Whitehead
manifolds. It is shown that whenever a 3-manifold in this class is a covering
space of another 3-manifold the group of covering translations must be a free
group. It follows that such a 3-manifold cannot cover a closed 3-manifold. For
each countable free group a specific uncountable family of irreducible open
3-manifolds is constructed whose fundamental groups are isomorphic to the given
group and whose universal covering spaces are in this class and are pairwise
non-homeomorphic.
