Ok guys my parents have a 2009 GMC 2500HD ext cab short bed 6.0 gas and it will be mine once I get my license. My question is it says it rated to tow 10,400lbs with the 3.73 rear end and 12,400 with the 4.10. We have the 3.73. Now does this mean subtract the truck weight from the 10,400lbs and whats left is what your trailer+load can weigh total? Or does it mean when I back up to a trailer the total trailer+load can weigh 10,400lbs?