When I click on the site is says page not found. Also, the differential assembly's block/body cannot be fixed. I called Steve at Pantera's by Wilkinson and he said once cracked thoroughly, they cannot be welded back together. Mine has the crack going all the way through the body of the block, from one side to the other, and half-way across one of the inlet holes. I also took it to a very experienced metal shop and the owner examined it at length and said it could be fixed, but it would cost so much money it would never be worth it.
I was lucky enough to find two used ones on eBay, and bought them both quickly yesterday. I also bought two rebuilding kits, so once I get them I will attempt at rebuilding them and hopefully have a spare.