No, that's how much the truck, cargo, passengers and tongue weight shouldn't "legally" go over........
There is a GCVW (Gross Combined Vehicle Weight) which is the truck, as listed above, and trailer.....
For Example (Since I actually have these numbers):
My 03 Excursion has a:
GWCR (Gross Weight Combination Rating) of 20,000 LBS
Maximum Trailer Weight of 11,000 LBS
So some simple math means the truck can weigh 9,000 LBS.... (Truck Curb + Passengers + Cargo + Tongue Weight)
Looking at the same chart for the 6.0 Powered Trucks, the max Combo for all of them is 20,000lbs, but the max trailer weight varies depending on the vehicle, transmission and trailer type (obviously mine will only do bumper tow).........
Take a look at the charts starting on Page 14 (This is a 6.0...FYI):
http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/0360l6d1e.pdf
Closest I could get for the IDI trucks was for a 96, and it doesn't list the diesel in the charts (That's in the diesel suppliment which I don't see)
http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/96f23og1e.pdf
Starting on Page 229.... list all gassers from a 4.9 RCSB F-150 through a 7.5 F-Superduty. For close numbers, I would look at the 7.5L listed truck
If you scroll up from Page 229, it even lists the axle and engine codes.....