Liouville and Toda gravity theories with non-vanishing interaction pot
entials have spectra obtained by dividing the free-field spectra for t
hese cases by the Weyl group of the corresponding A(1) or A(2) Lie alg
ebra. We study the canonical transformations between interacting and f
ree fields using the technique of intertwining operators, giving expli
cit constructions for the wavefunctions and showing that they are inva
riant under the corresponding Weyl groups. These explicit construction
s also permit a detailed analysis of the operator-state maps and of th
e nature of the Seiberg bounds.