well, I doubt the GVWR of the F250 has increased, at 8800 lbs, its under 9000 lbs because if it was over that you'd pay more in registration and insurance. So, the only way to increase the payload is to lighten the truck...
in 2002, the f250 and f350 had virtually the same frame, axles, wheels, brakes. the F350 had a extra leafs on the rear springs to increase the payload, and was stickered at a higher GVWR (9900 lbs with single wheels, 11200 lbs with dualies). interestingly, both 250 and 350 have the same GCWR of 20,000 lbs.