How about the Rokon Trail breaker. It is belt driven input and chain drive output is a three speed and kick start. I think it requires a one way rotation drive clutch to be able to kick start the engine. Not 100% sure about that part. The Abilon transmission in the pre 1973 Trail breaker is the one I had in my Mach III
Listed in the parts section of the Tule Trooper they show 3 transmissions that have multi disc clutches not that I have ever seen any.
I think that the Mustang scooters used a Abilon or Burman transmissions.
Takes a lot of looking around and some heavy duty cash reserves to buy some of these hard to find gearboxes.
Steve