Well, I may be off on my numbers. Things have sure changed a LOT since 2002. Here are a couple docs for you:
Payload/Weight Ratings
Tow Ratings
It looks like GVWR is 11,200 and it does look like GCWR is 13.5k. I find that hard to believe with a GVWR of 11,200.
Still, it's a Super Duty dually. I wouldn't hesitate to put 10k behind it as long as the dump box was empty and as long as you aren't going on long freeway drives.
Yep, you're right the GVWR is 11,200. With a truck that weighs upwards of 8,000 pounds, leaving 3,000 pounds of payload capacity and 5,500 towing technically. But again, like you said it's a super duty dually. I won't be swapping out motor or rear end, just wouldn't make sense, so if anything maybe look into a transmission cooler. As another poster pointed out, it does indeed have a trans. temp gauge, which I'm happy to have. I still have a year to save up and buy a tractor and trailer, so I'll try to make a few bucks with the truck in the meantime.