07-09 will all interchange.
In 2010 they changed the rear fender design to one with thinner number boards ala KTM, and to make it work they changed the rear piece of the airbox to a thinner piece. You need that new airbox half, otherwise the 2010 rear guard wont cover the airbox and it will leave a hole there. That's the only thing stopping you putting 2010-2011 rear fender on an 07-09 bike.