Ok, the Bronco II has the easiest radio to pull that I've ever done. Your model year is prior to needing the "ford radio tool" in fact, you should be able to do the entire job with an ordinary philips head (+) screwdriver.
start by taking out the screws across the underside top of the dash cowl. then pop out (just pull) the strip between the instrument cluster, and the metal (bottom) section of the dash (this is the strip that contains your head light plunger, rear wiper switch, cigaret lighter etc). This will expose about 5 more philips screws holding on the trim piece around the instrument cluster. Remove those screws, and finally the trim piece. You'll see that your stereo head unit is held in by 4 screws. Remove those, and you can slide the whole thing right out.
