I don't think that is normal. Have you checked your:

1) Carrier bearing & Mount?
2) Engine and transmission mounts?
3) Flex joints?


My first suspicion is that your motor mounts are dust. If so, your motor will move every time the torque changes and the trans and driveshaft will move along with it. If this is the case, your trans mount is probably shot as well and if this has been going on for a long time, the extra movement may have taken out your flex joints.


-tp