Since 2005, the F250 and the F350 are essentially the same truck. On the 250, get the snow plow package for the big front coil springs and sway bar on the front, and the 10K package for the helper springs on the rear. The only difference will be 2" vs 4" blocks on the rear, and the sticker on the door. Same axle, same rear end, same frame, same brakes, same suspension. Choose your tires wisely, they keep changing the choices on those.
I had a 2005 F250 with the big package on it and a pair of $160 Timbrens on the rear, it pulled my 13,700# toy hauler 5ver with ease. The rear end went down less than an inch when I hooked up, and that was measuring at the rear bumper, not over the axle which is the truer way to do it. Had to pull a 41' triple slide once about 200 miles, that set it down almost 2 inches. That thing was heavy.