We have some that bolt on or weld on and latch automatically from either direction. Gate has a 1" stub on it.

Know where we got them from, but don't have a brand name or a picture.

Not much help, am I? I'll try to get more info and do an edit.

Edit-they came from Norbco.- http://www.norbco.com/products/super-gates.php

They have a pic of their latch, but it doesn't show it very well.