when searching for rear ends, look for full floating 10.25" rear end. Forget about the F250/350 badges, it won't help. Bring your tape measure to verify spread on spring perches and overall axle width. When I swapped my axles for 4.10 axles (before installing 5.13 gears) I got them out of two different f350 trucks. The Dana 60 front came off of a dually. The only "conversion" needed was swapping the wheel rotors with the ones that were on my Dana 50 front end. It was a very forgiving undertaking. Spindles were identicle.

If you're going with a flat bed, does it matter if your wheels stick out a little further?