Yeah the splines are unique. I used to laser cut them from 8mm plate, but even that was not perfect and was either too loose or too tight. And before anyone asks, no I dont supply them anymore.

But you can make a disk out of 6mm steel plate ( or thicker ) and weld it to the F&P shaft. Weld it to the thicker part of the shaft, not the spline where the shaft is narrow. Then you can just bolt your propeller hub to this disk. You can make another disk with a 13mm hole to go on the front and clamp it all together. It works great and is strong.

On some of the shafts there is a raised ridge about half way along. If you weld a disk to one ond of the shaft you need to grind this ridge down, other wise you wont be able to slide the bearing over the shaft.

Glenn.