seelucas

ok so my 2006 outback 4cl is making a grinding noise when under power. i had this issue about 6 months ago and it was a wheel bearing (rear right). thinking the rear left has gone out i just replaced it, but no joy. sound is a constant grinding. it shouldnt be the breaks because i had an entire brake service, pads rotors new master cyl etc about 1 year ago. also i replaced the front cv axels about 2 years ago. Help!!! Rear Cv axels? i have lifted the car and done a check on all 4 wheels for play (12oclock-6clock rocking) no joy!