When I bought my truck, it had no wipers. I soon found that the wiper pivots were both broken - someone once upon a time had removed the wiper arms carelessly enough to pull the splines from the pivots. Reproduction pivots with splines attached are widely available for about $40 each from various catalogs, but I was able to find a NOS pivot, still in the Ford parts room envelope, for $18 on eBay. I couldn't seem to find any installation instructions, though - not even in the Ford service manual - so for those of you who are new to this stuff like I am, here's how to replace the pivot on the driver's side. (When I get another pivot, I'll show how to do the one on the passenger side.)
First, remove the retaining nut and bezel from the pivot on the outside of the truck. The pivot, no longer held in by the retaining nut, will drop into the cab behind the instrument panel, which needs to be removed to give you access to the pivot.
There are eleven screws holding the instrument panel and instrument cluster in place. The seven screws marked with blue arrows hold in the entire assembly. The four screws marked with yellow arrows hold the cluster to the panel. Remove all eleven screws and carefully pull the panel away from the dash. The glass behind the panel will also be loose, so be careful not to let it drop and break. Set the panel aside, but you can leave the cluster in the dash. Just move it over to the right to give yourself enough room to work on the pivot.
The pivot arm is shown in the photo above, marked by a yellow arrow. It's attached to the actuator arm with a spring clip. You won't be able to remove it with your fingers, and I found needle-nosed pliers to be too clumsy inside the dash, so I used a pair of locking forceps to grab onto the clip and carefully pull it free.
Keep the clip, you'll need it when you install the new pivot. Also, when you take the old pivot out there will be a thin steel washer between the arm on the pivot and the actuator. Keep that washer for the new one, too; it will save you having to run out and find a new one.
Take the old pivot out and look at the hole in the cowling where the new pivot will go. See that keyway at the bottom of the hole? Remember it.
The new pivot has a raised rectangular key that lines up with the keyway in that hole. That holds the pivot steady while the shaft inside rotates and makes the wiper work.
Attach the new pivot to the actuator arm. Remember to put the thin steel washer between the pivot arm and the actuator. Press the retainer clip onto the pin to hold everything together, then put the spline end of the pivot out the hole in the cowling, lining up the key with the keyway for proper fit.
Replace the bezel and retaining nut to hold the pivot in place through the cowling. Turn on your wipers to make sure the pivot is working correctly (the spline will move back and forth.)
To finish up, replace the instrument cluster and panel, and you're ready to replace the wiper arm and blade.