Gary, I have installed Quaife LSD's in my 4.5 and 4.8 diffs. I also use a 3.9 but have not installed the Quaife in that diff. With any of the sprite diffs, if you try and use locktabs under the LSD bolts, the bolt heads will interfere with the bearing carriers. I have found that loctite and no locktabs works fine. Paul