I got this 93 940T and it's not made me happy. One ongoing issue is vibrations. It vibrates sometimes at idle and sometimes not, so that's an engine issue or at least not driveline, and it vibrates/rumbles when driving that can be felt in the seat and the floor, so that's probably a driveline issue. It rumbles when starting out but that's the carrier bearing. Hard throttle up a steep hill reveals rumble, then vibration in the seat and floor, then in the steering wheel. This is consistent and repeatable.
The story so far;
had the center bearing shimmed. result, small improvement but not eliminated. Had the bearing and donut replaced; greater improvement but not eliminated.
Changed trans fluid; old was nasty. Result; improved shifting but still vibrates. (this seems separate from the rumble)
Changed trans mount 2x; the old mount was soft and somewhat misshapen and sort of coming apart but still intact. First one was a cheapie but only one available locally quickly. It didn't fit all the way down into the square hole in the mount but I tried it. first result; worse. second result with a German Beck Arnley that fit correctly, about the same.
While it was in the air we looked at the motor mounts and compared them to some known good used ones off my old car, and they seem fine. We ran the car while looking underneath and saw nothing obvious.
So, idle can be smooth but is often rough/vibration, not rough running. The engine seems normal when looking at it when the vibration can be felt. It's definitely not consistent. When driving, car is pretty smooth at 50 or so but gets bad around 65 and over 70 is terrible.
Rear wheels have been balanced twice. Front have no shimmy or other sign of issue, and I believe they were balanced recently also.
It has been mentioned that maybe the new trans mount raised the trans so the shimming that was done initially may now be way off, but I don't know if the shop that did it reshimmed to original, I'm going to find that out.
So to repeat, there seem to be two different things going on.
??????
Thanks