2000 Toyota 4Runner tail light /dash fuse blown

A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.

In this case, the obvious place to start is by unplugging the power antenna. That is run by the radio, and the radio has one of its two power circuits tied to some other circuit. The tail light circuit is often one of them.