Running board replacment

[liftingdoc]

Hi guys - quickish question. I've got an '08 X5 4.8i, had it for years, 110k miles. It came with the aluminum running boards, however my wife hates them and I'm not a fan either. I've been looking around trying to figure out how to just replace them with the original OEM parts, but I'm not even sure what they're called (side skirt?). I've been drilling this down with google and here, and found a lot about going in the other direction, but no luck with going back to the non-running board state. Thanks in advance.