The diagrams are great. If you have a stand alone trans there are Ram 2500/3500 manual trans pcm's available using only three of the plugs (C1, C2and C3). An Automatic pcm can be flashed with manual software, but there can be tuning issues. (been there with a 03 auto pcm) When doing a retro install, don't even consider using a 03 pcm. I would highly recommend using a 05 Ram pcm for the best tuning options. Good luck..