The sterling 10.25 actually has plenty available for it in the aftermarket. Lockers, spools, gears, set up kits, axle shafts, you name it.
There are so many super duty's where im from running around on 44" tsl's, boggers, 46" claws, and 49" iroks that the aftermarket had to dive into this realm. Everybody and their mother has lifted superduty's anymore, and its starting to show in the catalogues. Just check around and you should have no problem finding parts...
if you need them, that is. Good luck breaking those things on anything less than 40's.