I forgot to mention. you dont need friction modifier if you dont have locker rear end. look at your tag on the rear. if it has an L in the ID tag..ie..
3L55, 3L75 then its a locker if it reads 3. 55 then its open rear and no need for modifier. be careful with your modifier too much and you will render your locker useless, too little and she will lockup on corners. I usually add like 4-6 ounces then drive it if she binds up then add another ounce, till she drives nice.