Rockwell swap. Done, and get to roll 54" tires.
Ok you got some options.
Leaf sprung d60 from another f350
Coil spring d60 swap from a 2005+ truck
Swap to the d50? The frame mounts are there, just need the brackets.
Leaf sprung super duty d50/60
I recommend a reverse shackle swap and the 99-04 super duty axles. YES they are unit bearings, YES the lug pattern is different, but think of what you can do with a sterling 10.5 swap and all that braking power... Sky's Manufacturing sells rsk kits for pretty much any axle under and frame, ever 2wd/f150 leaf spring swaps.