Just to help you out with what the parts discussed do: the "bevel gear" and "angle gear" are the same part, people tend to interchange the terms. I think that "bevel gear" is the more correct version.

Anyway, what this part does is send the power from the transmission to the rear wheels for the all-wheel drive system. Picture the drivetrain as a "T" with the two front wheels at the top ends of the cross of the "T" and the bevel gear sends the power to the rear wheels, down the "|" of the the "T".

They do fail. Especially when the oil level isn't maintained, or the oil isn't changed.

The first generation Volvo AWD system (on the 1998 - 2000 AWD V70/S70)was found to need careful attention to AWD details like tire size, or the bevel gear got destroyed as the AWD system locked up on drive pavement and no front-rear differential action was possible.

But I have to say that in reading this board for about 8 years or so, yours is the first time I've seen anyone post with a second-generation AWD bevel gear failure. (not to say it hasn't been posted, I just don't recall one before)