Originally Posted by alaxfire

A U joint is generally used in a scenario where there is a large degree of angle varience between two spinning components in one plane. In the case of our cars, there is very little difference in alignment between the components, the flex disk is more for smoothing out the shock transients between the transmission and the differential.
A U joint has no value in shock dampening.

Of course, that's just my opinion, but I stick by it......