Thanks. It isn't trivial, but some Toyota#O hose will probably fit over that square slip joint. Yes, you will have to increase the diameter of the motor shaft - maybe some model aircraft fuel line?
Your original question was regearing - my original answer was yes, I regeared a W Challenger. Much, much easier to do my proposed test first -
you might like to avoid the really difficult gear installation stuff. It involves pressing, knurling (you need a lathe) and quartering, plus modifying the motor mount, etc., and in the end if you really want a flywheel it complicates the project considerably.
I have several Williams models - the PRR Turbine, a Mike, a PRR T1, and three of those really neat B6 switchers. All have that cheap Chinese motor, and all run quite well. The "J" was an anomaly. I think it is "hit or miss" with these things. But I assure you, the gears themselves are robust, and should not be changed.
I saved the gearboxes from the W Challenger. I will probably use them some day.
