For the most part then it's pretty much agreed. Unless you are out to do nasty things with HP and traction the 8 inch will do great. Remember to use the 67 and up case though. Ford redesigned the case in 67 for more strenth. Ford did decide to put 8 inch rears under eary 67 390GTs with automatics when they were short on 9,s. My Cougar has one.
