Hello,
I have been trying to hunt down this answer for you, but have been unable to find it as of yet. I would recommend buying a Haynes or Chiltons manual. You can purchase one used at eBay for a very small amount of money. Here is a link to get you started: http://search.ebay.com/search/search.dll?sofocus=bs&sbrftog=1&from=R10&submitsearch=Search&satitle=1980+bronco+manual&sacat=-1%26catref%3DC6&fmmk=&fmmd=&fylo=&fyhi=&mppfqy=1980+bronco+manual&sargn=-1%26saslc%3D2&sadis=200&fpos=02129&ftrt=1&ftrv=1&saprclo=&saprchi=&fsop=1%26fsoo%3D1&coaction=compare&copagenum=1&coentrypage=search
Best of luck!
CarGrrl
To remove the harmonic balancer bolt on an 80 model bronco get a one inch socket and an impact and zip it off.
In the shadetree mechanic style I have sometimes had to go as far as locking a set of vice grips on the pulley if there is room and then taking a boxend wrench and putting over the end where hopefully you can turn the pulley til the wrench touches the frame to keep it from turning when you try to take the nut off. Sometimes if you don't have an impact wrench available you can use a hammer (carefully) to tap the wrench in the direction to loosen it. Use a quick sharp tap and it should break loose. Be careful not to let the wrench get off sides or you may break the bolt. I have also seen people put a long wrench on that will butt against the frame or something and then bump the starter to break it loose.