castle nut for Gori prop

Make one. It is simple. These are just a standard nut and then you can use a hack saw to slot them. The easiest way is to load two or three hack saw blades side-by-side in the hack saw frame, mark the top of the nut with a sharp felt pen for where you want to grooves, put the nut in a vice, and cut the grooves. That is all these nuts are. Nothing special. You do not really need that many grooves. You really can get away with using one or two if you have a few washers of different thicknesses so that you can get a fit that is not sloppy. Or you can use the washer you have, put the nut on to see where a groove would line up with the hole in the shaft, and then just cut one groove. The cut will leave a small burr on the threads, but they come off as soon as you screw the nut onto the shaft a couple of times. I forget the size of the nut. I think it may be a 12mm. The shaft itself is 14 at the bottom of the splines, and 17 at the top.