If you need to change the glow plug controller you will find that every one says you need to take the inlet manifold off.
Today I found that is not the case, here's how I did it.
I started by taking off part numbers 5 & 8 here ( top and Bottom ) on the passenger side. (UK)
These sit at the bottom of the wheel arch and go above and below the drive shaft and steering rod.
RealOEM.com - Online BMW Parts Catalog
With these out of the way if you look up just to the left of the drive shaft you will see the controller held on with two 10mm nuts. these can be reached with a long extension bar.
The hardest part of the job is getting the main plug out of the controller.
Even so it only took 45 mins to change the unit over.
This may be the same for the 3.0 ltr as well.
Hope this helps.