I had an 02 Griz that had a very similar sound and it seemed like it was coming from the left side of the engine just like yours. Mine only had 1200 miles on it (I bought it with about 930 miles and big mud tires). The CVT had been reassembled incorrectly (roller weight fell out) and as a result the wet clutch was burned up from trying to turn the Outlaws. I had an ATV/sled shop replace the wet clutch and the sound went away. I wouldn't swear that you have the same issue but it might be worth a look since yours has higher miles.