It's pretty much a combination of "wheel didn't fall off, Car didn't explode, Car stopped leaking gear oil out busted wheel seal, and the unnatural failed wheel bearing grindy noise stopped". Mechanically a rear wheel drive differential isn't all that complicated. I like to think that if I can build a computer I was probably smart enough to at least bluff my way through installing a new axle with a chiltons instruction book thingy and picture diagrams. But we'll see if it holds up!