reading this against a pair I've bought second hand off a forum member, and he had no problems. THQ have said that no one could find the problem with the knocking, however they did, and its to do with a changeover in age of van, to age of bilsteins. theres small weld type dimples on the chassis of the van where the rear dampers connect too... and these dimples cause the knocking. Bilstein have since brought out a revised version of the "top bushing/balljoint thingy" to the damper, which is thinner, allowing no contact, meaning no knocking. THQ would grind down these dimples and treat the metal work accordingly, this sorted the problems they had. IM HOPING this will be me on friday, when i ask the garage to shave down the dimples when they align it.