For unitedracingdesign's Red Bull X2010:
You've been down too long in the midnight sea.
Go to your Assetto Corsa folder and go to: content > cars > urd_redbull_x2010/urd_redbull_x2010_s1 > skins, then drop the 'holy_diver' folder into it.
Dio Holy Diver Livery For Red Bull X2010 4K/2K v1.3
For unitedracingdesign's Red Bull X2010