As i took the air intake elbow off the airbox to fit the filter i noticed a bit of movement at the injection unit end. I removed the three bolts holding the elbow on and it appears that the injection unit is just resting on top of the inlet manifold

That can't be right can it!? There's a fairly substantial rubber gasket, but no bolts or anything securing it.
Can anyone confirm, or has anyone got a diagram/photo to show what(if anything) I'm missing?
Thanks in advance
