Twisted axles
I am not totally sure I want to go this route. My son said he can cut splines any size I want. These splines are a standard automotive spline in 1.5 inch size. The bearings would be larger then stock so I would have to machine the carrier out to accept them. This axle was quickly roughed out in a hour just to see what it would look like. I left extra material on the length to increase the amount of spline engagement. You can always cut it down but can't add. I would increase the diameter of the thread on the end.
Like I said I am still not sure I want to go this route,
Hope this works








