1. The Mercedes-Benz Owners' Manuals website: This website provides access to a variety of Mercedes-Benz owners' manuals, including the one for the 1980 240d. The manual should contain a vacuum diagram.
2. The Haynes Repair Manual for the 1980 Mercedes Benz 240d: This manual is a comprehensive resource for repairing and maintaining your 1980 240d, and it should also contain a vacuum diagram.
3. The Mercedes-Benz Service Manual for the 1980 240d: This manual is a more detailed resource than the owners' manual, and it should also contain a vacuum diagram.
4. Online forums and websites dedicated to Mercedes-Benz vehicles: There are a number of online forums and websites dedicated to Mercedes-Benz vehicles, and some of these forums may have vacuum diagrams for the 1980 240d available for download.
5. Contact a Mercedes-Benz dealership or repair shop: If you are unable to find a vacuum diagram online, you can contact a Mercedes-Benz dealership or repair shop and they may be able to provide you with one.
