I plan to replace the boot only. Not sure if I even have an air hammer - I need to go look. Can you use an air hammer if you leave the axle in the diff on the other end? What are you hammering on? Not sure I am getting what you are suggesting.

It wont...you can use the threaded bolt from this kit and the Slide hammer Flange (OEM27032) to try and push the axle end from the hub. I actually had better luck with a sledge hammer and a fat center punch.

Make sure you liberally spray PB Blaster on the splines and the hub when you're trying to push the axle free. Many years of rust will make this task almost impossible without it.

u have to disconnect the idler arm and then the whole unit moves and then u hit the shaft in the dimple and it separates from the hub.

the inboard shaft stays in the differential. You're trying to seperate the outboard shaft and the hub from each other. The axle doesn't need to be completely removed from the car if you're just changing the outer boot. Just make sure you support the axle from hanging down freely.