2002 V70 2.4 auto gearbox replacement
 

The auto gearbox on my 2002 V70 2.4 appears to be going home - evidenced by severe vibration at 50-60mph. Wheel balance and driveshaft/suspension issues have been excluded, and I'm reliably informed that the remaining possible source is the gearbox, the diff bearing being the most likely culprit. I'm looking for a fix at a reasonable cost, given the high mileage (220K+) on the car.

I'm aware of a low-priced AW55-50 box, described as belonging to a B5244T3 engine. My car has the B5244S2 engine. One question is, will there be any differences in fittings between thhe AW55-50 implementations on these 2 different engines? Or, indeed, among models with other engine variants?

More generally, is my assumption that replacement is the most appropriate fix correct?

All information/suggestions gratefully received.