'03 possible buy, questions regarding base 5cyl AWD system

[mrbrian200]

On an '03 XC90 5 cyl 2.5t AWD with 99k miles, How big a problem is the AWD transfer case and rear diff? I'm familiar with the rest of the vehicle as it would largely mirror my 2.5t FWD S60. I'm merely concerned whether I should be recommending and AWD model to a relative looking for reliable transportation under $5k. Or should I steer her somewhere else. She wants a mid size suv/crossover, wagon or minivan.

When I bought my S60 I keyed into potential problems with the AWD/angle gear, since I don't really need it simply avoided cars equipped with AWD (as well as the sure bet to strand you sooner than later T6s). Avoiding AWD on an XC90 appears difficult. But as I'm not expressly familiar.. is AWD system a sure bet to fail or can preventative maintainance such as seals/ new oil/bearings etc prevent wear failures on units that haven't already?