Hi, you can replace the universal joint, although it is not so easy as replacing the whole shaft.
But replacing the whole shaft is a bit waste of money, when only the universal joint can be replaced too.
But I would suggest to check if the noise is really coming from the shaft and joint itself, it could be from the diff itself.
Just position the car with both wheels on the ground, put transmission in neutral, and go under the vehicle. Try to move the propshaft, and see where you can detect some movement. Maybe in the universal joint, but maybe in the diff itself. It could also be in the propshaft, but that's not so common.
If it fails while driving:
Since you have AWD, I think you can lock the center differential? Or is it rear-wheel drive normally and you engage the 4x4 menually?
Anyway, once centerdifferential (or transfer case) is locked, there is always the same amount of force applied to both rear and front wheels.
This means that if you have an issue with your propshoft (or the universal joints), you can simply remove the propshaft and drive on. That means you turned the car into a front-wheel drive car
which will behave differently in corners, just drive carefully.
Just carry some spanners in the car when driving.
I have used this trick with an old Landcruiser, works just fine.