  The two-body Dirac equations for the bound q bar q systems are obtained from
the different (five) versions of the 3D-equations derived from Bethe-Salpeter
equation with the instantaneous kernel in the momentum space using the
additional approximations. There are formulated the normalization conditions
for the wave functions satisfying the obtained two-body Dirac equations. The
spin structure of the confining qq interaction potential is taken in the form x
gamma0 X gamma0 + (1-x) I X I, with 0 < x < 1. It is shown that the two-body
Dirac equations obtained from the Salpeter equation does not depend on x. As to
other four versions such a dependence is left. For the systems (u bar s), (c
bar u), (c bar s) the dependence of the stable solutions of the Dirac equations
obtained in the different version on the mixture parameter x is investigated
and results is compared with such dependence of 3D-equations derived from
Bethe-Salpeter equations without the additional approximation and some new
conclusions are obtained.
