Sorry to dredge-up a 2 year old post, but since I was in here looking for information myself, I thought that I would answer this question for future searchers:

I'm currently working on a '99 Sportsman 335 for a friend, and from what I have researched, the 335 and 500 were identical chassis, just different engines. The rod that you are asking about is the low-range gear box lever. The upper rod goes from the shifter straight back to a pivot on top of the trans almost to the rear axle out-puts. The lower rod goes from the shifter to a pivot point then onto a pivot on the transmission about 10 inches ahead of the upper rod's pivot. So, yes the rod will need to be replaced if your friend wants to use the machine's low-range.