Due to some errors made with the naming of vehicles and duplication of filenames - specifically in the B1 skinpack - some vehicles have not been showing in game. To remedy this, please follow the steps below.
1.) Locate and Delete
<rfactor install folder>\GameData\Vehicles\HISTORIC GT\HISTORICAL FIA GT\GTC-TC-76\PORSCHE914
2.) Locate and Delete
<rfactor install folder>\GameData\Vehicles\HISTORICGT\HISTORICAL FIA GT\LM-72\LM72911s
3.)Re-install the deleted cars via thisdownload, directly into <rfactor install folder> (It has the whole GameData/Vehicles/etc structure in it).
You are now 100% free of problem add-on skins.
4.) Download latest versions of B0/B1 skinpacks.
5.) Install skinpacks as normal.