Why would the previous owner do this?

I had a 71 Ferd LTD back in '91, that I welded the Spiders in just for fun, and It was a way for a broke Georgia Boy to Try to get a 429 to hook up. I didn't do it that way I pulled out the top and bottom gears and completely seam welded the side gears to the case. Was insanely strong for what it was. I drove that car for a couple of years, absolutely abusing it as much as possible while daily driving it. That 9 inch never broke ( in fact I still have the third member in storage somewhere) the down side is i had to replace the rear tires every couple of weeks. lol David