You do not need to download a separate installer if you own the game on Steam. You can downgrade your current installation using these steps: Right-click Euro Truck Simulator 2 .
From the drop-down menu, scroll down until you see temporary_1_36 - 1.36.x for incompatible mods .
When you downgrade to version 1.36, any DLCs you own that were released that period (such as Road to the Black Sea , Beyond the Baltic Sea , or Italia ) will remain active. How to revert to older version of ETS2? - SCS Software
New UI tools allowed players to mark specific areas to avoid on their GPS. How to "Download" and Revert to Version 1.36 (Steam)
Steam will automatically "update" (downgrade) your game files to version 1.36. Accessing DLCs in 1.36
Select Properties and navigate to the Betas tab.