For starters I will be using a 4BT. The question I had was could I use an Eaton Fuller 6 speed? I know it's a big transmission, but I can get them slightly used for dirt cheap out of a buddy's scrapyard (same for the engine). The main reason I would be doing this is because we make our own biodiesel that runs in any diesel motor, even a 2013 F350 with no problems. Plenty of other reasons to though. Even if I can cram it in there is there a company(s) who makes all the necessary parts and pieces? As for Dana's I won't be climbing Mount Everest with it or sinking it over the mirrors. So mainly it's going to be a daily with some moderate trail. Should I upgrade to D44's or higher?
Thanks in advance.