This is an idea I had to make a smaller two speed gearbox. The CIMs drive the ball shifting gears directly. The intent is to add a second stage of reduction with gears or chain in the drive rail. With these gears (11:60 and 18:54) the spread is pretty close (1.82), but I think it's workable. A modest second reduction stage can get you approximately 8 and 15 fps.
Three CIMs are shown, but my instinct would be to run only two to save weight and avoid brownouts.
The motors are too close together to fit the stubby air cylinder, so a standard one is used.
All of the ball shifter components are stock, except for the pneumatic coupler, which has to be modified to accept the 1/4-28 thread on the air cylinder.
CAD files can be viewed and downloaded here:
https://workbench.grabcad.com/workbe...gMqJSJWmkkcnvL
The next hint will be game hint #3. Everyone will go crazy trying to figure out which of the fake hints was hint #2. - Joe Ross [more] 
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