The 13300 gvwr models should have a 30000 gcwr, where the 13000 gvwr models should have a 29000 gcwr. Subtract the loaded truck weight from the gcwr to get the trailer tow rating. Depending on truck model and options, the trailer tow rating will vary by quite a bit. 30000-8300 (rough empty crew cab drw weight) leaves 21700 for a trailer. Super cabs and regular cabs are lighter leaving more weight for the trailer. Don't forget, every pound you load in the truck lowers the trailer tow capacity.