I have just purchased my first trailer, a fifth wheel. While I plan to buy another tow vehicle next year, I will have to use my existing truck for a while. I have a 1996 5.7 L GMC 4WD truck. The Manual gives the tow rating at 6000 but does not reflect the factory tow package. How do I find out how much the tow package adds to capacity, or if it adds anything at all? My trailer dry weight is 6200. I would appreciate any advice.