Good Luck! Get as much back spacing as possible. It sounds like you are going with cast. In that case... get as much offset as possible. You may have to switch over to 5x4.5 and get FWD wheels in order to tuck.
As far as how much to narrow the rear end it all depends on the wheels. The less backspacing you have the more you narrow the rear. If you narrow too much you will also have to rebuild you frame rails narrower. I do not have my Dakota here to see excatly how wide a wheel you can run before you have to narrow the frame rails.
As far as how much to narrow the rear end it all depends on the wheels. The less backspacing you have the more you narrow the rear. If you narrow too much you will also have to rebuild you frame rails narrower. I do not have my Dakota here to see excatly how wide a wheel you can run before you have to narrow the frame rails.