Yes, '02 was the last change to the airbox and to the plastics. For that reason alone, I really wish my yz was an '02 instead of an '01.
My guess is that whatever difference there is with the cases wouldn't make a difference on the bike, but can't help to validate.
If you're finding them cheap enough, it's likely worth the risk as the worst case would be you re-selling the cases for a profit ;-)