Put on about 150 miles with the M56lk in the S60. I have delrin bushings for the shifting assembly and the shifter. I'm using 5w30 (currently) in the trans. The shifting takes some work - I have to give a medium-amount of effort into shift into each gear (couldn't do it with 1 finger). It doesn't just "fall in" to each gear like I'd expect.
When I installed the Quaife I installed new bearings for the axle-side, but this shouldn't have any affect. Any ideas?