Possibly, but there are enough large bearing models to know that even if there were more small bearings sold, the big bearings were not rare by any stretch. And I believe all full-size Broncos and most full-size trucks had big bearing 9" setups.
For the torque, it's good you asked because some of the books are wrong. In the Hayne's book for example (full of typos!) it actually lists 60lbs as the rating for all with a 9" rear. But that's obviously a misprint since while that's fine for a 1/2" bolt that's right at the limit of the small bolts and way beyond their official ratings.
I could not find an official rating in the Chiltons' book, but it would be great if someone who has a Ford manual can find the specification and let us know.
In the generic torque tables provided in the aftermarket manuals, a Grade-8 1/2 bolt can go to 92lbs without trouble. Even a Grade-5 is rated at 60lbs.
I've used 60lbs as my go-to for a long time now (because I assumed they were grade 8's!) but have also used 45lbs as the generic without any trouble. But always with locking nuts like the factory used.
Basically the 40lbs that is listed by the companies and that the others here are recommending sounds like a good plan.
For those with 3/8" bolts, I'd probably limit that to no more than 30-35lbs.
Just make sure that your locking nuts are still locking. Don't want any of them backing off. Not as likely in an application like this of course, but they're locking nuts for a reason and you want to keep them that way. So if yours go on too easily and will no longer lock themselves in place wherever they are, replace them with new nuts.
As a comparison I've had bad lock nuts on axles that stayed tight for a long time until they were replaced. While the ones on the leaf springs would loosen up regularly no matter how tight I torqued them.
So it's probably a good practice to make sure ALL your locking nuts still lock.
Paul
