Sorry to hear of the bad luck.
Those trucks are not really that hard to steal at all, the older gm 3/4 and up didn't even use chip-key. Pretty much as long as you can tilt it, you can take it. Even now most of the base model 3/4 tons are standard key as they are used alot in commercial/lawn/excavating/etc business and those guys just make cheap copies of keys and hand em out.
Hope you find it, or had good insurance.