Josh, this is Rod...here's something that I always look at when I build or rebuild diffs. If you look very closely at the thrust bearing, you'll see that one side of the inner race has a slightly more conical shape and the other side will have a slightly flatter shape...We've been told that diffs turn out better when the flat side faces the cap screw the concical section faces the nut on the other side of the diff. I pack that lil bearing with Mobil1 grease (lifetime supply for like a buck at Pepboys). I use the Associated silicon lube (the red label grease) for the diff balls (good combo so that there isn't any excess diff spin, but may have a bit too much stiction). I save the Carbide balls for big races and use the relatively cheap "lightweight" balls for club and practice. Another important thing is to have a clean diff plate whenever you build/rebuild the diff. Flip it over if you need to lol. And when you reuse diff balls/thrust bearings...use A LOT of Motorspray to clean them. When you initially tighten the cap screw, don't crank down on it right away, just do it in like two-three steps and work the diff at each setp by spinning it in your hands. Do the final diff adjustment in the car. I hope this helps but please know that I am not exactly a world class diff builder ha

On the belts the rear white ones get tore up rather quickly with 6-7 turns and there really isn't much I have done to prevent it...sorry can't help you there. It seems that some belts new out of package require a different belt setting...I typically start all of mine at two clicks tighter for modified.

XingXing-yes the belt does get close to the servo stay and on occasion it'll rub but it's not that big of a deal. One of my original 415's no longer has blue anodizing on that side of the servo stay