Yep. The housing is just stamped and formed steel, with some decent sized tubing for the axles. Back in the day, a simple cable or bar truss was added (mostly to fronts, but also to rears) to add some support and keep the flexing to a minimum.
The fabricated "back brace" was a real boon as it was super beefy and you no longer had to sacrifice ground clearance to get the support.
Upgraded housings like we're talking about are a step above and don't necessarily need the extra reinforcing for most of us, but a back-brace is still desirable if you're really going to go out there and beat on it. Or if you're just going to have a little too much fun and are running 35" or larger tires.
As you'll no doubt here around here, they last just fine under quite a bit of abuse for most of us.
Some of the extra features of our Super-9 (
http://www.wildhorses4x4.com/product/17600) are:
The use of the later housing centers which are wider for more support.
The centers are V-cut ("fishmouthed") at the axle tube junction for even more support, more weld area, stress riser reduction (or at least a change of the dynamic).
Billet steel big bearing outer ends with the large 1/2" bolt hole pattern.
Spring perches already welded on at an appropriate angle for a modern 10 or 11 leaf pack when used in an EB. Means you are very unlikely to need tapered shims to align the pinion when used with a lift kit. Not sure how far off it would be with stock springs though. No feedback on that yet.
Smaller diameter axle tubes (a good and bad point perhaps?) for added ground clearance.
All at a pretty decent price level actually.
The added clearance with the axle tubes is more a byproduct than by-design. It's pretty much a necessity these days, as nobody we could find manufactures a center housing for use with the original 3.25" diameter tubes. And all the original cores from the junkyards have been picked clean with few exceptions. So other than used, you don't find 3.25" centers anymore.
Still, it's a stronger option than just a stock '77 and later housing due to all the other upgrades.
Hope that helps.
Paul