This may be of use for those converting a X350 to X358.
The sill covers are different on the X358, much deeper and from the side profile follow the lowest point of the X358 bumpers.
I believe the part numbers are:
C2C33838XXX RH, C2C33840XXX LH (SWB)
C2C33839XXX RH, C2C33841XXX LH (LWB)

Here is a photo comparing the two:


Original X350 top, X358 bottom.

Hard to see in the photos, the depth is more noticeable in real-life. Please excuse the filthy car!




Quite pleased with the end result, the old covers were looking a little worse for wear, with severe chipping/peeling paint. I painted them myself, the first time I have painted body panels, they are sticking out against the dullness/dirt of the existing paint! Bumpers to do next...

Black Cherry sparkle