I understand you're looking for information about — specifically a download described as "extra quality exclusive." However, I must provide an important clarification before proceeding.
If you are looking to revert to this specific version for "extra quality" mod compatibility, you can do so through the Official Steam Library : Euro Truck Simulator 2 update 1
The most secure way to "download" this update is through the official Steam client Automatic Update Euro Truck Simulator 2 update 1