I think you'll need to be more specific about the location of the leak - assuming you can see where it comes in. Only if it's coming in right at the driveshaft hole would your supposition that it involves the drive bellows apply. If water is entering there, the cause would be the bellows leaking.
Can you see where the entry point is? If not, what's at the highest point where you can see water (or evidence of a drip)? Is it up by the steering cavity?