First, they probably aren't "dual action". Most lever shocks work only on rebound, not compression. Second, "knee action" was a self-contained suspension system that was used on cars in the late 1930's, never on trucks. It was not very successful, and was discontinued pretty quickly. A lever-type shock should have very little restriction as the spring compresses, and a fairly stiff resistance as the spring rebounds. It sounds like your shocks have lost their fluid, probably due to bushing wear and/or worn seals.
http://theoldmotor.com/?p=159035Jerry
