How much play or movement(front to back) should I have in the spline on the front driveshaft in my 420SEL? Mine is totally compressed, with nut loose,no movement to rear of car at all. Flex disc is unable to come loose even with carrier bearing loose. I've changed the engine in car, and am in process of bolting everything together.I feel I should have enough movement to allow flex disc to be removed . I think I need to shorten my driveshaft, but need to have an idea of how much.