Both skins were supposed to be part of the ADFX-01 mod, however since we stopped developing it, here are the F-15Cs at least
Both skins go to C:/users/[you]/Saved Games/DCS.openbeta/Liveries/F-15C
If you dont have the Liveries or F-15C folders, youll have to create them.
UPADTE:
Fixed an issue with the wings
