Leaky diff

So I have a bad pinion seal on my rear diff, i have everything apart and ready, but the seal Rockauto sent me looks wrong. The old seal can be removed where the yoke enters the axle, But this new seal makes it look like i'd have to take the whole diff out to put in. Did I get the wrong part, or do i have to take my whole axle apart?

Compare to another seal. Any autoparts stores around? I think I picked one up at Orielly's when I did trany and 3rd member seal. Did Rock auto supply an image with the AD?