I believe if you have somebody read the manual to you, he or she will explain that conventionally towing trailers exceeding 6,000 lbs. or 600 lbs tongue weight requires an equalizing hitch.
The towing specifications for 6.0 Powerstrokes are in the Diesel Supplement tpo the Owner's Guide.
http://www.motorcraftservice.com/pub.../0660l6d3e.pdf
Please figure it out before driving on public roads!