Traction-Lock...What to use as friction modifier?

[Rev]

Recently had my 8" Currie Traction-Lock redone. Had spring loaded clutches inatalled instead of the Currie Torque Sensing Differential. Now the car vibrates and chatters when going around corners. Lubricant is Mobil 1 synthetic gear oil 75-90 wt. It's supposed to be good for limited slip, but the thing does chatter around corners. Ford used to recommend a "friction modifier" for the Traction-Lock rear ends. Does anyone know exactly what that stuff is. I've thought about adding STP oil tratment or Motor Honey to the gear oil to see if that would help. If anyone has advice or comments, I'll appreciate them. Thanks.

Rev

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'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.