I've got a driveline shudder when under power. The car drives smooth as silk as long as I'm not on the gas, but as soon as I give it any power, there's a shudder and grumble from the driveline somewhere. It sounds like it's coming from the back end.

It was worst when it first started. I was doing about 70 when it suddenly sounded like I had a motorcycle in my rear right blindspot, but it was coming from the car, and I could feel the shudder in the gearshift. It faded and went away entirely over the next 1/2 mile, but returned a shortly, and is now bad enough that it seems risky to drive it.

-Dirk R