You can start here, but Rob L. may be able to say RM8 and get you started in the right direction. The Windsor parts manual spells out the correct size of the bearing at the base, but not the ball size for the twenty-four balls you would replace on the worm ends.
http://mapleleafup.net/forums/showth...eering+bearing
See also:
http://mapleleafup.net/forums/showth...=Steering+worm
http://mapleleafup.net/forums/showth...=Steering+gear