If its the seal where the propshaft goes in Holz Racing Products || ATV - 450R || UTV - RZR RZR-S || Sled - Rev IQ RMK also makes a whole new pinion flange and everything for only $50. Comes will seal gasket and new aluminum piece. You have to take the whole dif out anyways and they claim that its strong or better or whatever.
How many miles/hrs you got on your rzr? I just noticed mine leaking a couple weeks ago and replaced it at about 75 hrs.