The 1.40 update overhauled the lighting engine, making old "flares" and textures look blown out or pitch black.
Look for the "Models" or "Trucks" sub-forum. Users often post "Fixes" for abandoned mods in the comments of the original thread. ets 1 mod fixed
Fixing Your Favorite Old Mods in Euro Truck Simulator 2 (ETS2) ets 1 mod fixed