  We present the derivation of the NNLO two-parton final state contributions to
top pair production in the quark-antiquark channel proportionnal to the leading
colour factor $N_c^2$. Together with the three and four-parton NNLO
contributions presented in a previous publication, this enables us to complete
the phenomenologically most important NNLO corrections to top pair
hadro-production in this channel. We derive this two-parton contribution using
the massive extension of the NNLO antenna subtraction formalism and implement
those corrections in a parton-level event generator providing full kinematical
information on all final state particles. In addition, we also derive the heavy
quark contributions proportional to $N_h$. Combining the new leading-colour and
heavy quark contributions together with the light quark contributions derived
previously, we present NNLO differential distributions for LHC and Tevatron. We
also compute the differential top quark forward-backward asymmetry at Tevatron
and find that our results are in good agreement with the measurements by the D0
collaboration.
