The reason why the box fits is because, the 6, & the 8 use the same block. What I mean is that both the V6, & V8 are cut from the same cloth. Just one is poted to be an 8 cyl and the other for a 6. If you look on the engine it self, you'll notice a lot of open holes, with no screws in them. Thats that way for two reasons. One is for diff. comp. for the SLK32, and the Second is for added Comp. for an 8cyl motor. If you look at the coil packs on the engine block towards the firewall. You'll see ther is actually an open spot for a fourth coil pack, on both sides. I thought that was kind of a smart play on mecedes's behalf. Hell you'll save a boat load of money doing it that way.