just installed a used set on mine. You will need to order 2 bags (about 50) of 51111944537 expanding rivets. When installing the wheel arch trims, install the footboards loosely, then the wheel arch trims. You will need to fine tune the positioning of the footboards so everything comes together nicely, then tighten.

btw: I have a set of all four wheel arch trims for E53's with running boards for sale btw. They are 5/10 in condition, no cracks, tears, etc. You would need the footboards, lower valance and upper trim to complete the set.