Nismo made LSD's for the H150 & one came up for sale recently on Yahoo. It was assembled into a H150A differential with a 3.7 to 1 ratio & came with a recomendation that it be dismantled, checked & overhauled if necessary.
The winning bid price, plus shipping & handling charges would have meant that an Australian buyer would have been up for about $1,350 to $1,450 landed at his door.
Plus any repair costs of course.

They are quite rare, but hey, you only need one.

You could give Bprojects a try. They are very helpfull.