It sounds like alot of you guys tow big stuff. What is my truck rated to tow? And how much has anyone actually been able to tow with no problems? I just saw a new crewcab 4x4 dually towing a double decker car hauler with 2rangerover suv's and 2 midsize cars on it! Wow is that legal?
The 1999 towing guide shows your configuration is rated at
13,100 lbs for 5th wheel towing, when equipped with auto trans, tow pkg, and 3.73:1 rear axle.
I don't know if that figure changed for 2000.
My configuration (see sig) is rated at 13,800 lbs. You are giving up 700 lbs of towing in exchange for your 4wd and crew cab vs. my supercab config.
That is just rating. What these trucks can actually pull is much more, but at the cost of safety and increased wear on your drivetrain components.
What year was the 'new' truck you saw? The newer (2009+) trucks have substantially higher towing capacity, especially if it was a F450. The 2012 line is rated up to 24,400 lbs of towing for the F450, and around 16,000 for the F250/F350 SRW and the dually bumps the cap to 22,000.
Ford only wants you to weigh a total of 20,000lbs truck and trailer. Some states go by that, others allow you to register it for what you want. Some people have towed WAY more then 20k and it'll do it (ever see a gooseneck full of round bales??). Your stock trans won't like it though.