I saw some on e-bay awhile back. They went for around $100 each.
But now that I'm lookin for some,none to be had.
Oh! While I think of it. STRONGLY suggest you use a transfercase!
If you try to use a dual output shaft trany,where is the front drive shaft gunna go. Unless your going to cut the dump box,& stick the tany in there.Remember,the drive shaft has to be telescopic for diff movement.
There tons of things to use for a transfer case. One of my favorites,is what travis showed you. Most of the time,I mod the f-350 trany for my dumps.That seems to be the best route for me. You can pick them up all over.(cheap!) Then if you go that route,I'll show you the mod I do to them.Then there the perfect speed.( Nice & slow). & this will cost you around $50-70 TOTAL!
FGD
Good luck!