From what I find, here are the specs for your truck, 11,500 GVWR, 3922 max payload, if 4x2, you have a 13000 max 5th wheel capacity, if 4x4 you have a 12600 max 5th wheel cap with 3.73 or 4.10 gearing same either way. Your GCWR in 20,000lbs. That all is based on a crew cab with 7.3 diesel pickup. So with all that being said you will either need to upgrade your truck or downsize considerably your expectations for a 5th wheel. That info was on fords tow rating website. Feel free to double check it. Not trying to burst your bubble so to speak just want you to have realistic expectations as to what your truck can safely handle.