Got my S60 installed last week. After the install I had a gear noise between 40 and 55 MPH while under steady throttle and it was driving me crazy. Called DTS and they had me bring it in to swap the gears out. Swapped the gears and the noise was still there! I watched the install, I know for a fact they built the rear PERFECTLY. So they told me to break them in and if I had any more issues to bring it back and they'd do right by me. Really great guys there, I will never take my car anywhere else for rearend work. Fast forward to yesterday when I was starting my clutch install - I get under my car and put the jackstands under the axle to get it as high as I could. I start looking around under there and find that my torque arm is resting on my floorpan! No wonder I was hearing the gears, it was metal on metal 6 inches from the differential yoke. I have an aftermarket torque arm, which makes a difference as well, but that has to be why it was so loud. I dropped the axle down and did the BFH mod, so hopefully when I get it back together it won't be loud anymore. I'll post up the results when I start my clutch break in.

 

i had to modify my spohn tq arm to fit my s60. i to cut the first set of holes on the plate that bolts to the top by the pinion on the housing. in the floor pan hard. it was a third gen. my rear is quiet. but mine is also an automatic.