Put all the shims on the gear side. And use about 5 spots of diff grease on the gear. Keeping the gear moist will help it last longer. Most don't put enough on it and it gets dry enough to start flaking. Then it shears a gear. By shimming it tighter and keeping it moist it will last longer under higher power motors and hard braking. I don't sand my diff rings either. I just break them in slowly with a drill before installing them. I tighten a bit at a time 4 times till its ready to be installed and set. And you will note the T nut wont bottom out when you set the diff. And you will have more adjustment. I have 4 very smooth weeks on my diffs, heading for 5. I think the thicker tolerance is overall better for the spring tension on the diff. I doubt it matters much though.?

Sanding diffs are good if you want more grip instantly, but I have never had one last as long as I have not sanding them. Some will disagree and to each his own. And I do the thrust rings to and just ain't worth it to me.