Replacement of the four wheel drive actuators on a 2004 and up F150 system is actually quite easily accomplished. You only need a handful of tools. I will have to double check, but you should need a 21mm socket, impact, hammer, 13mm socket, 8mm socket, pliers, and a large prybar. Sounds easy enough right? Any mechanic worth his weight should own these basic tools If you don't, you should really go read about my Recommended Tool List.
Of course, you also need a well lit work space and proper equipment to lift the side to be repaired to completely suspend the wheel and let all the weight off the suspension on that side. That means a lift, or that means a jack with appropriate jack stands. Never lay under a vehicle without jack stands. Replacement of the actuator should only be performed once diagnosis has concluded and determined that you have a failed actuator. Directions and tips for proper diagnosis and part requirements can be found on my other article F150 4WD 2004+ System Diagnosis. Even if you think you don't need to read it, you should read it to help double check your own diagnosis.
Some tools will make your job easier, such as a Air Hammer Kit to help separate a stuck axle from the hub or to punch the tie rod end out. Some prefer using pickle forks or even the fork attachments for your air hammer Pneumatic Pickle Fork Set. Care should be taken when removing any tie rods or ball joints as the threads can be easily damaged. You can also smack the spindle with a hammer to free stuck joints, but that too comes with risks.
- Jack up the side to be replaced, completely removing weight from the suspension.
- Remove tie-rod end nut and separate the tie rod from the knuckle.
- Remove center metal axle nut cover. Sometimes easy to do with pliers.
- Remove axle nut. The tiny tiny axle nut. Use your hand to push the axle shaft in a bit. Should take much force on these trucks.
- Remove the upper ball joint nut. Then use force to separate the upper ball joint from the knuckle.
- Pull entire knuckle assembly forward and turn to the side a bit while pushing the axle shaft out of the center.
- Carefully guide the axle shaft from the center of the hub. Can be difficult but will fit. Sometimes removal of a brake hose bracket bolt and or a speed sensor wire harness hold down bolt gives you more room to maneuver the knuckle.
- Remove the three bolts holding the actuator, and remove the actuator. Inspect splined surfaces of the axle and hub for damage.
- Replace with new actuator. Reinstall bolts and tighten. Extra carefully reinsert the axle into the knuckle but be careful not to damage new actuator.
- Perform rest of installation by reversing disassembly procedure.
I have included a few pictures to demonstrate what it looks like when disassembled. Here is a picture with the old actuator removed, and here is a picture of the new actuator installed.