Just to make sure I was clear, I meant where is the power plant for an Astartes who is wearing the ammo-backpack of a heavy bolter? Is it built into the ammo-backpack?
Ahh I see.
The pictures here show that the ammo backpack seems to be slightly different from a regular back pack, but yeah it does seem to be built in to the power plant.
EDIT Insert cheesy fast and the furious quote. "Damn that guys fast!!" I agree with the Baron.