Jack the front end up and grap the tire. Put your hands at the 12 o'clock and 6 o'clock positions and move the wheel back and forth (push in with one hand and pull out with the other). If there is play in it then your wheel bearing is probably out. Also take a good look at the cv joint boots and see if there is a tear in it. If there is it's most likely the one at the knuckle rather than the front differential. My buddy's '05 sportsman 400 started to pull really bad and was even locking up on him (and getting clunks) and he had to get a new axle for that side. The boot got tore and all the grease came out. More than likely it's gonna be one of the two. Let us know what you find out!