I have a 2005 M and I am running the 10.4 secondary. You can buy the piece from arctic cat that rivets into the stock bellypan so this clutch clears. You will also need the rivets and the metal protector which keeps the secondary from wearing through the bellypan if you did hit something underneath. It is farily easy to install as long as you have a dremel or a rotozip to cut out the stock bellypan in order to fit in the new drop pan.
If you look at a part schematic for the M8 the belly pan is the same as the earlier models and the piece I am referring to under the secondary is sold seperate of the pan so there is no point in buying a new belly pan, just buy the parts and add it to yours.