Here's a link to RC4WD it shows the three different models they make.
http://store.rc4wd.com/Transfer-Case_c_24.html
I have the killer transfer case and it's pretty stout. Takes a licking but it's a 1:1
not sure if you want reduction as well but they do have that as well.
There are a few other manifacturers as well but most of those are harder to come by because they have been out of stock for a while.
--Dan