X iv :a st ro -p h/ 04 09 37 9 v1 15 S ep 2 00 4 Strong-Field Tests of Gravity Using Pulsars and Black Holes M. Kramer, , D. C. Backer , J. M. Cordes , T. J. W. Lazio § , B. W. Stappers ‖ S. Johnston ∗∗ University of Manchester, Jodrell Bank Observatory, Jodrell Bank, UK Department of Astronomy, Univsersity of California at Berkeley, Berkeley, CA, USA Department of Astronomy, Cornell University...