Last night I was out driving on my 2004 600 sportsman when the right side axle stripped where it goes into the diff. Seems to be a pretty bad design by Polaris. Water/dirt gets in there and chews the splines out same as the rear drive shaft. Anyone else have this same issue? Just wondering how common this is. Don't want to spend hundreds on a repair for something that will likely fail again.
Thanks for any input

 

There have been some that have had this same problem,but overall not a common problem. The heart of the matter is that the gear(#18) now isn't offered separately like years ago. You have to buy the complete rear diff now. Manufacturers only stock so many parts per model and once that runs out the only thing that they may have in stock is the complete diff. Have to figure the machine is almost 13 years old and beyond the normal 10 year span on supplying all parts for a particular machine. You could try a use rear diff on ebay.2004 Sportsman 600 rear differential | eBay
Plus these models use the same ones as yours.

Usage : 1341352 Rear Gearcase

Year Product Model Assembly
2004 ATV A04CH59AF SPORTSMAN 600 REAR GEARCASE - A04CH59AF/AH/AJ/AT/AV (4987468746D01)
2004 ATV A04CH59AK SPORTSMAN 600 REAR GEARCASE - A04CH59AK/AL/AN/AQ/AW (4987468746D01)
2004 ATV A04CH68AC SPORTSMAN 700 REAR GEARCASE - A04CH68AC/AF/AH/AJ/AT/AV (4987468746D01)
2004 ATV A04CH68AK SPORTSMAN 700 REAR GEARCASE - A04CH68AK/AL/AN/AO (4987468746D01)
2004 ATV A04CH68AU/CU SPORTSMAN 700 REAR GEARCASE - A04CH68AP/AQ/AU/CU (4987468746D01)
2004 MIL SPORTSMAN 700 MILITARY GEARCASE, REAR - A04CH68MB (4986128612D01)
2003 ATV SPORTSMAN 600 REAR GEARCASE - A03CH59AA/AF/AG (4987468746D01)
2003 ATV SPORTSMAN 700 REAR GEARCASE - A03CH68AA/AC/AF/AH/AL (4987468746D01)
2002 ATV SPORTSMAN 700 REAR GEARCASE - A02CH68AA/AB/AC/CA/CB (4966346634D01)