Re: 12 bolt hp rating
I have used 12 bolts all my life, and I have broken a few, but I had a lot of fun doing it, and they gave years of service before dying. The stock 12 bolt is stronger than a stock 9" Ford rear end (that's a blue oval not Strange, or Moser, or Currie custom made with the only Ford part being a bearing retainer cup).
I have never met any one who has broken a Dana 60 (not saying it can not be done), but if you did it routinely they do they make a Dana 70 that looks just like it, and with out a tape to disclose the 10.54" ring gear available in any tooth count you could want, you could not tell them apart. Break a Dana 70, and it is time to get a Rockwell rear end out of a cement mixer.