Hey cain, to tell you the truth, I just had the size for the diffs in my extra parts. Im not even sure what size they are, I dont have a micrometer. As far as running bearings in the diff. I always felt they were a must. Bushings wear after time, and in a place such as the diff I feel they will wear and get sloppy. I have bearings in all of my 4 wheel cars diffs. They make the diff smoother and are more reliable. Some may not agree. Its my opinion and choice