  The MSSM distinguishes itself from other GUT's by a successful prediction of
many unrelated phenomena with a minimum number of parameters. Among them: a)
Unification of the couplings constants; b)Unification of the masses; c) Proton
decay; d) Electroweak symmetry breaking. A combined fit of the free parameters
in the MSSM to these low energy constraints shows that the MSSM model can
satisfy these constraints simultaneously. From the fitted parameters the masses
of the as yet unobserved superpartners of the SM particles are predicted. The
2nd order QCD coupling constant is required to be between 0.108 and 0.132. It
is shown that a top mass of $174\pm16$ GeV, as suggested recently by the CDF
Collaboration, constrains the mixing angle between the Higgs doublets in the
MSSM to: $1.2<\tb<5.5$ at the 90% C.L.. The most probable value corresponds to
$\tb = 1.56$, which leads to a stop mass below the top mass. In this case the
stop production in $p\bar{p}$ collisions would contribute to the top signature.
This could be an explanation for the large effective $t\bar{t}$ cross section
observed by CDF.
