Well I got my gears about a week ago and they are whining. The weird thing is, my STOCK 3.27 gears whined before I had the new gears put in. The whine isn't terrible, but you can definetely hear it, and it sounds like it's coming from the rear. Tomorrow I'm taking it back to the mechanic and he's going to check the backlash. The whine only occurs from 2700 RPM's to 3000 RPM's. So far I have only noticed the noise while in second and third gear. Do you guys think maybe the gears aren't the problem since my car did the EXACT same thing at the same RPM's with my stock gears? Maybe it's the T45? Nontheless, the car is going in tomorrow to be looked at. I'll drive the mechanic around. Also, I should add, 75-140 Mobil 1 is in the diff, but the mechanic said friction modifier was not needed . This is a reputable gear shop....