  We investigate the universality of truncation schemes for Dyson-Schwinger
equations developed for quantum chromodynamics in theories which differ from
quantum chromodynamics only in the gauge group. Our specific choices are the
gauge groups $SU(2)$ and $G_2$, for which lattice calculations at nonvanishing
chemical potential are possible. Thus, corresponding calculations can provide
benchmarks for testing calculations with functional equations. We calculate the
quark and gluon propagators and determine the chiral and dual chiral
condensates at vanishing density to determine the confinement/deconfinement and
chiral transitions, respectively. We can reproduce the expected type of
transitions in the quenched and unquenched cases. In general, all three
theories react very similarly to modifications of the employed model for the
quark-gluon vertex.
