Hello John,
Make sure the bearing seat in the axel tube is not worn. Sometimes the bearing will sieze and spin. Eventually the area will wear causing play. If the bearing has spun, the area where it seats will often times be polished shiny from the spinning bearing. You can solve the problem by using a center punch and some Locktiite srud and bearing mount to tighten up the housing around the bearing again. See the "rear axel tour".
Take care,