i have an early 2003 dodge ram 2500 heavy duty with cummins HO engine, 6spd manual 4x4.  almost stock, pretty much my work truck. not my daily driver. but cummins for the win for sure, my diesel i had before was a 97 ford f 250 with the 5 spd manual tranny, 4x4, and the good ol 7.3 powerstroke engine.  loved the truck, and loved the engine.  but now that i sold that and have my cummins, i gota say im a cummins fan now, but i love the older 7.3 diesels , and would still buy one if i could find an older model that was maintained well and doesn't  have a million miles on it yet...., but ya , im def a diesel fan for sure. even tho mine is my work truck and i dont drive her aton. but when i do , damn, its hard to beat that cummins / manual tranny package , thins hauls like there aint nothing behind it.  pulls my 3 horse , indoor tack room, fully steel trailer without even breaking a sweat, and alot of times i also have my camper on with the horse trailer in tow. and it handles everything without even breaking a sweat, even better than my old 7.3 .   have not owned a duramax so cannot say anything good or bad about them, but i know i would never by a duramax for myself.