how hard is to change engines in a 1990 f 150 from 300 6 to a v8 302 out of a 1991 bronco what all do I have to do my truck is 4x4 too standard trans

 

You need the complete engine, wiring harness and computer, frame towers and engine mounts, exhaust Y-pipe, rad and hoses, all V8 accessories and brackets. It's lots of work and hopefully your truck has at least 3.55 gears or it's gonna be a dog.