When I got my 1978 Corvette, back in 1979, I remember the first time I went up an exit ramp off of the freeway and when I hit the curve and stepped on the brakes, the rearend chattered really bad. I took it to the Chevy dealer and they said the only thing that would stop this chatter in the plates was whale oil. That is what they used to put in the Corvette differentials. But since it is illegal, they now have a synthetic fluid they use. It is expensive, too.