Whenever I accelerate my transmission moves up an inch or two. Of course I only see this inside the car by watching the shifter. But if I put any strain on the drivetrain (accelerate) the whole shifter raises straight up, and it goes back down if I let off the gas. I'm sure a little movement isn't much to be concerned about but how much is normal? I've never been in another M6 Fbody so I have no idea.

 

Sounds like a tranny mount. Easy to do yourself.

 

I agree, sounds like a busted tranny mount.

 

A good idea to check your tranny mount.

The torque arm that controls the rear axle pinion angle is mounted to the tail of the tranny via a rubber mount. Under hard acceleration the torque arm will rotate causing your tranny to move somewhat.