just in case, marlin now sells these
EDIT: why doesnt someone just make these?
I mean, make some pins, with a lath, and a bolt? and a spring loaded alignment pin?
shoot, you could even make it work WITH a BENT axle? make an adapter that slips into the diff and current seal? (gives accurate reading of how your slightly BENT axle might need to seal?)
and make the other one fit IN the spindle bushing,
both would be less work as well as more accurate?