I actually have an article somewhere in one of the mags where they built a D50. The article was called "The Other Dana Axle" or something like that...
I think they said the outer dimensions on the pumpkin are equal to a D60, but it's smaller internally. That means the case is really thick and strong.
They listed the pros and cons. IIRC, the biggest "con" was lack of aftermarket support, however the point of the article was that there was finally some support for it (gears and lockers), hence the build. Again, IIRC, the thing ended up being nearly as strong as a 60 for a lot less money.