In a gear diff i use the plastic body washers for shims the lexan material for some reason works better for me. I use a metal and lexan washer on each side and the when I build the diff i adjust the screws to how tight I want the diff its almost like an adjustable diff. I put it in the car slap the two chassis halves together turn the wheels oposite each other and if its not tight enough I screw in the 3 screws that hold the cover on its a cool little technique that works pretty good. But keep in mind I just built a TA03 ball diff and a Gear diff that was not fully packed with anti wear grease but just enough to keep the gears well greased and the TA03 ball diff weighed 19 grams and the Ball diff weighed 28 grams almost a 3rd more in weight
