has any one   cross reference   a bearing  for a 21 cf 800xc  part # 9GQ0-050710

I havent and don't, but could you take it to a Fastenal or some such and get a reference for it?
I can't think of the outfits name right off, but theres usually a place that specializes in bearings around population hubs.
They usually deal with timken or federal mogul and can find about anything.

 i find  the hub bearing   unfortunately  these are only for the front

800xc has to different  size bearings  i need the rear   part # 30411-03080       DU3006037