Yes, would think so. With the ZF the diff is dropped in from above/below so can be fitted either way around.
With the UN1 the casing splits down its centreline so I also think it can be potentially be fitted either way although I've only ever seen the box fitted in the OE diff down manner.
With the Porsche and the Audi then access to the diff is through a plate on one side so I assume that this means the crown wheel must always be on this side so they are not reversible.
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