hey does any one know if there is an after market wb for the rear of a sportsman 500 if so what is the part #

 

Take the old bearing to your local industrial bearing supplier and they will match it up. The number on the bearing is a standard SKF (or whatever) # not a P part# so the old one is all they need. It will most likely to be a special order but should only take a couple of day's to get. Buying from a bearing supplier vs P dealer can save you upto 50% depending on what discount you can negotiate. Here the cost from the P dealer is $80 CAD, I paid $40 CAD per brg.
Good luck.