I have a feeling its time to replace mine. I remember when I 1st had installed my new tranny, poly mount, clutch and aluminum driveshaft. It felt good and I could really tell the difference on the highway with the new driveshaft. Now I can no longer tell the difference. At times when cruising at 70mph on the freeway, I feel a wierdvibe. Its as if something is turning and when it gets to its certain part of the turn, that when i feelthe vibe. I know it sounds wierd and its hard too explain it better then that.