[glassdoctor]

Nevermind the above pic..... you already said the stock bearing is 10mm.

Also I measured the stub on the kyosho which is right about 10mm. It's just a hair under 10 then tapers to just over 10. I wondered if you could use a spacer sleeve to make the stock bearing fit right on the kyosho... and fit at least part way onto the fat part of the stub. Just a little sanding on the stub and the bearing would fit. That would let the stock outdrive fit farther into the diff... maybe enough to work.

Make sense???

The problem then is that it's still a mod1 gear and you are using a MM. 1/8" bore mod1 gears are a pain... maybe Mike could hook you up with a spacer so you can use the 5mm gears.