Nuclear charge distributions for projectile-like and fission-fragment-like reaction products were measured as a function of angle and energy loss at each of the three bombarding energies EL=505, 610, and 710 MeV for the Kr86 + La139 reaction. The charge distributions at most angles and energy losses are dominated by a peak centered close to the Z of the projectile. The variances of the Z distributions of this component exhibit a different dependence on energy loss at each of the three bombarding energies. A nucleon-exchange model incorporating the effects of the Fermi motion and Pauli Principle is quite successful in accounting for the rate of energy loss per exchange deduced from the charge distribution data. This result suggests that nucleon exchange is the major mechanism for energy dissipation in these collisions. The data are also analyzed in the framework of a phenomenological model from which diffusion constants are obtained. For large energy losses a second peak appears in the charge distribution with a most probable Z equal to one half the sum of the projectile and target Z. This component is attributed to fusion-fission. The magnitude of the fusion-fission cross section at 505 and 610 MeV is larger than time-dependent Hartree Fock predictions. NUCLEAR REACTIONS Nuclear charge distributions measured as a function of angle and energy loss for Elab=505, 610, and 710 MeV; analysis with nucleon exchange model incorporating Fermi motion and Pauli blocking; transport model diffusion constants extracted; fusion-fission cross sections deduced.