Assuming it’s in your mods folder, I would say make sure you select it during the save game loading screen by verifying it has a check mark below the mod icon and then look for them under Medium Tractors.
It’s alphabetical in the J’s. A common practice with most players to ensure all are selected is to toggle “deselect all” followed by “select all”. If that doesn’t work then it’s installed in the mod folder improperly.
