he's talking about the block itself, the m/n just means valvetronic or not, I remember when the 4.8 came out C&D did an article and said that the way they added the extra power was to change the stroke on the 4.6 and add valvetronic

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2006 BMW X5 4.8is Lemans Blue/Beige/Dark Maple
-Nav, Comfort Seats, Heated Steering Wheel,
Rear Airbags, AUX Input
2009 BMW M3 Space Grey/Black/Carbon
-all options