Overview
Did some poking around….This process also works with the 26 speed transmission mod as well. I’m still testing this myself so please keep any comments regarding problems/ crashes to a minimum.
The Details
Open your C: drive (or whatever directory you have steam installed to)
Open Program Files (x86)
Open steam folder
Open steamapps folder
Open workshop folder
Open content folder
Find the folder that has your ATS mods (in my case folder “270880”)
Find the folder for each respective engine mod (every mod should have a “mod_description” text file)
Once found, open def > vehicle > trucks
Copy “peterbilt.579” folder
Rename the copy “peterbilt.389” witho/ quotations
Open 389 folder and find “mx” or “isx12” text files then open them in notepad
Same as renaming the folder, change line section “isx12.peterbilt.579.engine” (or mx depending on which engine mod) to “isx12.peterbilt.389.engine” witho/ quotations
IMPORTANT: use File Save, not File Save as
Close all windows after everything is saved
Launch ATS and confirm that the engine mods are active in your load order
Enjoy
This process should also work with the 26 speed transmission mod as well. I’m still testing this myself so please keep any comments regarding problems/ crashes to a minimum. I have no idea how to make them compatible with non vanilla trucks.