I don't know if you can still find them, but it hasn't been too long since I got a new idler arm bushing from the local NAPA. Looking at
http://www.rockauto.com they do show one but its listed for a 4x2 not a 4x4. From what I've seen it looks like the idler arm shaft and bracket are the same from 4wd to 2wd, but I have not measured the two side by side. The bushing can be a real challenge to get out of the bracket but once replaced it will take the slop out of things.
On one of my trucks the bushing was long gone, the bracket was well worn into, and the shaft was also basically a loss due to wear. So, you may end up needing replacement parts even if you go with a new bushing. It would certainly be easier to get a bracket and shaft somewhere to refit while the truck is still all together. Then you just have to fight the worn out stuff off and slap on the replacement.