  In this note, we consider possible constraints from $t \bar t$ production on
the gauge bosons of theories with an extended strong interaction sector such as
axigluons or flavour universal colorons. Such constraints are found to be
competitive with those obtained from the dijet data. The current $t \bar t$
data from the Tevatron rule out axigluon masses ($m_A$) up to 900 GeV and 850
GeV at 2 $\sigma$ and 4 $\sigma$ levels respectively. For the case of flavour
universal colorons the data rule out a mass ($m_C$) below 800 GeV (780 GeV) at
the $2 (4) \sigma $ level and also the mass range between 900 GeV to 2.1 TeV at
2 $\sigma$ level, for $\cot \xi = 1$, where $\xi$ is the mixing angle. For
$\cot \xi =2$ on the other hand, the excluded range is $m_C \lsim 950 (920)$
GeV and $m_C \gsim 1.02 (1.15 \lsim m_C \lsim 1.8)$ TeV at $2 \sigma$ ($4
\sigma $) level. We point out that for higher axigluon/coloron masses, even for
the dijet channel, the limits on the coloron mass, for $\cot \xi = 1$, may be
different than those for the axigluon. We also compute the expected
forward-backward asymmetry for the case of the axigluons which would allow it
to be discriminated against the SM as also the colorons. We further find that
at the LHC, the signal should be visible in the $t \bar t$ invariant mass
spectrum for a wide range of axigluon and coloron masses that are still
allowed. We point out how top polarisation may be used to further discriminate
the axigluon and coloron case from the SM as well as from each other.
