So I'm thinking about buying a new truck because I could get a hellacious deal on one....

I have a 1990 f-250 diesel thats not going anywhere, so I'm thinkin a 4 door half ton. After looking on fords website the FX4 seems pretty damn good right off the lot, diff. lockers stood out, don't really want to tear into the axles of a new truck to install Detroits. It comes with the 5.4 and I was wondering what would be the best programmer that I could mount on my dash and change engine settings while driving. This is a fairly simple question but I am not up to par with anything that has to deal with gasoline except for my dirtbike, nor am I used to working on anything new...