If you need an inline filter for ANY auto trans, there's a more serious problem occuring as there's a reason why the fluid's getting THAT dirty to begin with. It's like putting a bandage on the real problem.

Now..........Volvo has a TSB (or TNN) on XC trans fluid and fluid flushes SO that's what should really be done instead. They have synthetic ATF available for XCs that's recommended BUT also VERY costly if out of warranty. If it's within warranty and there's a shifting problem that's relating to fluid condition, the fluid flush with Volvos synthetic ATF is covered. The stuff costs about $15 per liter and 16 liters are needed to properly flush it according to the TSB (or TNN) regarding the proceedure.