XD- equals extra duty maybe? Don't know, but this truck fails to excite my taste. Cummins 5.0 nice choice, good bridge possibly between the 1/2 -3/4 ton perhaps. Still don't care for the styling, but never have. Looking forward in seeing toyota offering using the same engine. Me.. Well sticking with my truck cause I need the 3000lbs of payload. Smaller camper then I would consider a light duty truck, but that's not going to happen for many years. Time for that baby Dmax to find its way into the gm twins 1/2 ton offerings.