yes, so i see...well the pin idea is possible as id have to fabricate cutters to do a spline which would get expensive, plus i dont have access to a shaper (just to add insult to injury), which is a machine that is really good for cutting internal splines.
both cogs are different sizes too , it gets worse .
shame a few savage diff gears or 8th scale buggy diff gears would not work see how you go with the brushless mate...

its not 5.43 in the morning, im not that sad. its 10.44 lol.