Take a close look at the dirt and grime that has accumulated in the underside of the vehicle, especially near the axle...that's what will penetrate the bearings that the axle boot is supposed to protect.
Needless to say, prolonged exposure to such coarse sediments will ruin precision bearings in short order!
There are some universal kits available that will allow you to just cut off the old boot and fit a new one without removing the axle...has fasteners along one side of the boot perimeter and a radiator hose clamp-type fastener surrounding the boot area.
I've used these on my VW without problems...you might be able to find the kit in a local well-equipped auto store...