There are a bunch of them in wrecking yards, seems in NC they range from around $175-300 depending mainly on the yard.
I can give you the number of a yard here that I know has one more, I think they want something like $250 for it, just call and have it shipped. I've looked at it and it seems good, stored indoors and good input spline. Surface rust on output flanges. Wake County Automotive in NC, located near Raleigh.
I just didn't get it as I found some that were just as good for $200.
I've got a 5N and 3U, but want to keep both. 5Ns and AAZs are the only thing in the States that I know of.
R