My 3.9 Ford engine over heated

So i bought my 2004 Ford Mustang about two years ago and just recently i moved to Flagstaff, Arizona. My 3.9L decided to turn evil on me and i took it in to Midas and they said that i have a potential engine block crack. So now my mustang is completely useless because the radiator is no longer working and i have a crack in my engine (Supposedly). I am hoping someone can help me figure out a solution. I've been looking online for a used engine either a 3.8L or 3.9L. I can't come across anything that catches my eye because i do not trust buying a used engine online.