Yesterday I reinstalled my drive shaft. The carrier shaft center bearing had failed, and sidelined the Ford until I got it replaced. This is a non-trivial job that often requires the loving touch of a driveline shop; on some vehicles the bearing can be trivially replaced, but on most (including this one) it must be pressed on and off.
A carrier shaft, sometimes called a propeller shaft, is the first part of a two-part axle. This name may only apply when there is a bearing at the center, I'm not sure; mine has one. Oddly, the replacement part I purchased from Kragen was the wrong size. A little research indicates that I have a rear wheel drive axle, although my pickup is a 4x4. The driveline shop was able to get me a part where Kragen wanted literally days to ship one, and I got it substantially cheaper as well.
Installation is fairly simple because both splines (at the transfer case, and the end of the carrier shaft) are keyed, so-called "blind spline" designs. In actuality, neither is truly blind; you can start the spline engaging even in the wrong position, but they only actually slide together fully when in the correct position. As such, it is necessary to inspect the splines before assembly to ensure correct orientation. Since you need to apply grease to these splines before they are connected, this is not an arduous requirement, but it does require some forethought. Propeller shaft bearings are torqued to about 50 ft-lb, and the little 5/16" bolts that hold the U-joint to the rear diff input yoke only take 8-15 ft-lb. I used thread locker on all of them, since these are high-vibration parts.
The cost ended up being about $140 in shop time and a bearing at Transmission Exchange in Lakeport, CA. The other shop I called in Lakeport quoted me about $90 when these guys said about $75, not including parts. On a crusty old truck like mine, these prices can easily stretch, but usually the shop with the lower estimate comes out cheaper in the end. We'll never know, but I was very happy with my experience, and would definitely use this shop again.