There is also an additive you should put in the rear end
oil with a Limited Slip 3rd member, it is made specifically for this and will reduce the "chatter" and make you LSD work better.....if it is out and apart, look at the clutches, you should see a "pattern" on the clutches itself almost identical to a clutch disc, if the clutches show no pattern and are smooth, they are worn and I would replace them, otherwise,put it back in the car and add the LSD additive (avaliable at any Ford dealership or parts place) with the rear end
oil.....
David