I know your looking for the reduction drive... but tower does have some of there products..
I bought the miller big grip for my Dynatron starter.. I have the same starter
if you run it in parallel with two batt. it bumps up to 24 volts and it's very strong... starts my zdz 40 and DA 50 no prob
you may already have known but just a thought

Ron

Heres a link http://www2.towerhobbies.com/cgi-bin...er&FVPROFIL=++