Hey man i sell lots of wheels at work and spline drive wheel nuts is the way to go and they are cheep can$$ is about 90$ for 32 of them for a ford superduty so they should be cheeper for 20 of them pm me if you have ???
went to halfords today
no joy there asked assitant about locking wheel nuts for a pontiac bonneville and the bloke ran a mile and i didnt see him again so gave up and came home
oh well the motor is a bit rare over here so cant expect him to have even seen one before
will try a few other places and see what happens then :(