On my way up Cobb Mountain I started hearing and feeling click/thump noises from somewhere in the middle of the truck. It turned out that the carrier shaft bearing's rubber isolator had failed, probably because of added vibration because a bolt was falling out. I was lucky enough to have an appropriate wrench handy, and made it home; as long as you are very gentle on the accelerator you can even go up hills with the isolator broken, but jam that pedal and THUMP THUMP THUMP as the bearing bounces around in the bracket.
The Ford factory "service" manual, which is the worst I've ever seen, has nothing on the procedure whatsoever. The only mention of the carrier shaft bearing is an admonition to inspect and replace it if you have removed the drive shaft. The drive shaft R&R procedure is there, at least, but it has no revelations beyond marking the shaft when you remove it to preserve balance. The manual asserts that a blind spline is used, which I hope means keyed, but I'll mark that, too.
As a side note, I took a look through some various lift kits that are sold for this truck, and as funky as I thought it was, the lift bracket set in the Rough Country kit seems to be the beefiest available. That's especially interesting since it's the cheapest available as well. It seems that unless you are having a custom lift built it is probably far and away the best buy. If I had it to do again, I think the only thing I'd change would be to omit the steering stabilizer, and buy that and the steering rack from Superlift. I may end up doing this anyway, but I can always sell the stabilizer, which will fit any TTB F250 with up to a 4" lift.