What is the fuse box diagram for a 1991 Lincoln town car?

To answer your question EXPLICITLY: the fuse box diagram IS the fuse box diagram. If your question is: Where can I get a fuse-box-diagram for my car?, then first I would direct you to the Owners Manual for your car. These usually contain a fuse-box-diagram. If this is unavailable to you, check the reference-section of any large-city library. In the 629-section there are usually shop-manuals that contain this type of information.