If u have what's called a 4 cyl Aussie, ( I'm asumming that is what u have.) u can only use that in a 4 cyl style diff. The difference is carrier bearing size. So u need to match up the Aussie to the correct diff style. And I do not recommend putting the high pinion in the rear, they have a tendency to break. and the high pinion is one that came out of a landcruiser axle, that is correct. And they are interchangeable.