I have a 89 F-350 with a 460 and a 5-speed behind it. I am thinking the rear end is geared for towing but I dont really tow that much with it and if I do its not alot of weight. I was wondering if I could drop in a powerstoke and maybe get some better MPG with it. I really love the diesel and would love to drop it in there.I am some what new to the Ford world so work with me. would I also have to change the gears in the rear to get have a speed of 65 at a lower RPM. Right now at 65 I run around 3 grand. If anyone could help me with finding some things out I would appreciate it. I will post pics in a different post in the new members area.