Can anyone give me the Gross Combined Weight Rating for a 2019 GMC Sierra 1500? It is a 4WD crew cab short box with 3.23 rear axle ratio and max tow capacity of 9,400 pounds. The payload limit is 7,100 pounds. I have found anywhere from 12,000 to 15,000 pounds for combined truck weight and tow vehicle. Thanks in advance for the help and info.