When I installed 6.5mm hex extenders on my Typhon, the screw pins wouldn't fit the driveshaft so I had to use the standard pins. Since I was worried about the pins falling out, I made this sleeve that slides over the hex behind the tire to hold the pins securely in place.

I have included multiple different sizes to fit your application. If they don't fit your hex extenders, just message me and I will try to help.