  We have studied the variation of $e^+$ and $\bar p$ top of the atmosphere
spectra due to the parameters uncertainties of the Milky Way geometry,
propagation models and cross sections. We have used the B/C data and Galprop
code for propagation analysis. We have also derived the uncertainty bands for
subFe/Fe ratio, H and He. Finally we have considered a neutralino induced
component in the mSUGRA framework. We conclude that even in the case of
diffusion convection model for the standard propagation, where secondary
spectra gives a good fit of the data, SUSY contribution can not be excluded up
to now due to the overall uncertainties.
