The process of installing mods for Euro Truck Simulator 2 is relatively straightforward. Most mods come in the form of .scs files, which are essentially archives that contain all the necessary files for the mod. The standard procedure involves:

The "Old Versions" or "Archive" sections of the official forums are goldmines. Many legendary modders keep their old download links active via MediaFire or Mega. Recommended Mod Categories for 1.28

Check their compatibility archives. How to Install Mods (Version 1.28.1)