  In this paper we give an elementary proof of the proper homotopy invariance
of the equivariant stable homotopy type of the configuration space $F(M,k)$ for
a topological manifold $M$. Our technique is to compute the Spanier-Whitehead
dual of $\Sigma^\infty_+ F(M,k)$ and use the results of Spivak and Wall on
normal spherical fibrations to deduce that the Spanier-Whitehead dual is a
proper homotopy invariant. This stable invariance was recently proved by
Knudsen using factorization homology. Aside from being elementary, our proof
has the advantage that it readily extends to ``generalized configuration
spaces'' which have recently undergone study.
