Here are the best places to look:
* Your Owner's Manual: The most obvious place to start. While not all owner's manuals include detailed diagrams, some do. Check yours thoroughly.
* Haynes or Chilton Repair Manuals: These aftermarket repair manuals often have detailed vacuum diagrams and other helpful information for specific Toyota models and years. You'll need to specify your exact model and engine when purchasing.
* Online Forums and Communities: Toyota-specific forums (like those found on sites dedicated to car enthusiasts) are a great resource. Search for your specific model year and engine; someone may have already posted a diagram or have a link to one. Be sure to specify the engine (e.g., 4A-C, 20R, etc.).
* Online Parts Websites: Some online parts retailers (like those selling parts for classic cars) may have diagrams in their online catalogs or searchable databases. Search by your vehicle's details.
* Local Auto Parts Stores: A local auto parts store may have access to repair manuals or databases that contain the diagram.
* Toyota Dealership (unlikely but possible): While less likely, a Toyota dealership *might* have access to old diagrams, but this is not guaranteed and may be costly.
In summary: You MUST know your exact 1978 Toyota model and engine to find the correct vacuum diagram. Without this information, locating the diagram will be extremely difficult.
