IMHO towing ratings are unimportant when it comes to towing a fifth wheel.
What you need to know are three things.
Real ready to travel weight of the truck.
GVWR of the truck.
Real ready to travel pin weight of the fifth wheel.
Lacking any of these items and you are only going to be guessing.
Lacking this information you might make a couple of assumptions and be close.
The current crop of 1 ton SRW crew cab truck with diesel and automatic is going to scale ready to travel right around 8000 pounds.
So, subtract from the GVWR 8000 pounds and generally speaking you are going to have around 2000-2500 Cargo Carrying Capacity (CCC)
Again generally speaking a fifth wheel is going to have between 17 and 25% of it's total weight as pin weight. Most folks consider 20% a good place to start. So, using my example above of 2000 pounds CCC on the truck and basing on 20% means you can tow a 10,000 GVWR fiver.
This is all based on a lot of assumptions and assumes you want to stay within manufacturers numbers otherwise you probably would have never asked the question in the first place.
