Just as the title states, the driveshaft has about 1/4 turn of play. The only two things I can think of are the center bearing (which looks healthy via inspection), and the rear diff (which is a 30k mile VLSD, was also having this problem with the factory open diff). Anyone experienced this problem? The car is getting to the point where it is horrid to drive because of the vibration, noise, and loud clunks when on and off the throttle, due to the driveshaft play. It is getting so bad now, that the clunks from when the driveshaft's "slack" goes taut, under throttle, can be felt in the shifter as well as the rear end, and can be heard from outside the car as a loud clunk. Driving at low speeds the problem is more noticable due to the absence of road noise. I can literally tap on and off the throttle at low speeds and get (clunk [on], clunk [off], clunk [on], clunk [off], etc.) I just recently destroyed a ACT 6 puck clutch I had in the car. What happened to it is the center splines, where the input shaft bearing goes into, got rounded out, and I'm willing to bet its do to the problem I am having. You can imagine what this problem must be like and what it can do to those splines under a hard first to second shift, which I believe is how the 6 puck broke.

The car is a S13.