Far Cry 5

You will need to grind this by AFK, start by going to the right path to the tractor, drive the tractor to the back of the barn. You will want to position the tractor where it doesn't block the exit you will know you kill zombies if they go to the tractor's front killzone but keep in mind your tractor will be moved a little bit so do not forget to fix the positioning when it happens. This grind took me 7 hours.