Paul,
IMHO a mistake of any gear box design is the omission of a
damper. If you don't run one between the shaft and the gear box, you at
least need a harmonic balancer style one to help kill the resonance.

Everyone also has the wrong idea on lubrication. All gear boxes should
have
their own lube system and use a synthetic gear lube.... like the shell
aircraft turbine gear box lube. Turbo prop engine gear boxes have used it
for many years.... using engine oil in the gear box is a mistake IMHO.

Larry

Larry,
I have the same thoughts and am pleased someone with the experience confirms
it.
George (down under)