Manuals
i have the DC manual for our trucks. IF you are going to get ONLY one, then i would recommend the DC FSM. it gives lots of engine info, but adds all the info on the rest of the truck. plus, the engine info is specific to the dodge ram cummins. i haven't seen the cummins manual, but if i were going to do some serious engine mods or overhauls, i'd want to add the cummins manual.
my 2. 5 cents worth... ... ...