Originally Posted by Jamie57

That is the much rarer CV or Constant Velocity joint type of axle.
And yes it does need that rubber cover to be in great shape without any tears in it. He is correct in telling you to get it fixed. The grease on the joint will become contaminated from the elements and fail when you probably need it most.
Most of us have the "Normal" Ujoint style. It looks just like the universal joint on your drive shafts. They do not need covers to keep them clean. They are also much stronger than CV joints.
ALL D30 axles can interchange with that style of axle.
Any way you look at it the hub bearing must come out. That is the blots holding it onto the steering knuckle the arrows are pointing at.
After the axle is removed from the axle housing you can either change it for the exposed Ujoint style or have your CV Joint "Boot" replaced if the joint has not suffered to much damage yet