  The classification method of the free fermionic heterotic string vacua is
extended to models where the $SO(10)$ GUT symmetry is broken directly at the
string scale to the Left-Right Symmetric subgroup. Our method involves using a
fixed set of basis vectors which are defined by the boundary conditions
assigned to the free fermions before enumerating the string vacua by varying
the Generalised GSO (GGSO) projection coefficients. It allows the derivation of
algebraic expressions for the GGSO projections for each sector that generates
massless states in the models. This enables a computerised analysis of the
entire massless spectrum of a given choice of GGSO projection coefficients. The
total number of vacua in the class of models chosen is $2^{66}\approx 7.38
\times 10^{19}$. A statistical sampling is performed and a sample size of
$10^{11}$ vacua with the Left-Right Symmetric gauge group is extracted. We
present the results of the classification, noting that contrary to the previous
classification of Pati-Salam models, no three generation exophobic models were
found. The results obtained demonstrate the existence of three generation
models with the necessary Higgs representations needed for viable spontaneous
symmetry breaking, and with a leading top quark Yukawa coupling.
