I've got an 82 that has the LG4 and a T5 in it. When I drive 60, there is no vibration. At 65, you can start to notice it. At 70, it shakes the whole car and feels like it is coming from right between the seats. I was thinking it could be the u-joints. The pilot bushing was replaced last weekend when I changed the clutch, the trans mount was in good shape. It's less than a year old. When I put the car back together, I rotated the driveshaft by 180*, thinking my vibration was coming from that. Should I just rotate it back to where it was, or change the u-joints? Naybe both?

 

i cant beleive it, this is the exact same thing that is goin on with my car, if you find out what it is let meknow