For my clarity, I just consulted the 2011 Duramax owners manual.
K2500 pickup - 4WD CrewCab with Standard Box and 3.73 Axle Ratio - max trailer wt 16,700 GCWR 24,500
It further states max pin weight of 15% to 25% of trailer weight up to 3500 lbs max.
Using 15% of GVWR 14950 calculates to a pin weight of 2242
Using 25% of GVWR 14950 calculates to a pin weight of 3738 but as stated the max is 3500
The Jayco site shows a hitch weight of 2530.
So I would calculate that that you could add 970 pounds of pin weight until you reach the max limit for that truck.
Interestingly that same truck configuration in a K3500 one ton configuration gives an additional 300lbs on the max trailer weight (17,000) and no difference in GCWR (24,500).
Moving to a DRW K3500 is where you see a big jump in capacity in both TW and GCWR.