To know the exact type and amperage of each fuse, you must consult your owner's manual. The manual will have a fuse box diagram showing the location and rating of each fuse. You can also often find this information online by searching for "1981 Ford Thunderbird fuse box diagram"
Trying to determine fuse types without this information is unreliable and could lead to replacing fuses with the wrong rating and potentially damaging your electrical system.