ie, obtain pictures of where they normally crack the casing, then have a company weld strengthening plates on the outer casing.
basically bracing and strengthening the outer casing.

As Jase is looking at this - its something we spoke about last year, but since then ive bought a thickwall diff.
im sure the extra bracing would aid its strength slightly, but need to see pictures of any that may have already been done, and to hear owners comments to see if its held up to the job whilst driven in anger!