Ok, if its a crew dually, it will be a V30, not K, and the rear will be a D70 as these are standard dually rears for the fleetsides whereas the cab-&-chassis models will have the narrower 14FF dually rear.
Just think of it this way: any GM 1 ton dually that came with a regular bed (with the wider fenders) will almost ALWAYS have a D70 and those with no beds or if they have utility beds, flat beds, etc, they will likely have the 14FF.