Vibration is definitely a drivetrain vibe, the shifter vibrates like crazy, and it increases a LOT under load, especially in 4th gear at 3500+ rpms. It vibrates when I rev it in neutral as well, which is why I don't think it's the driveshaft like everyone told me.
The car body itself has almost 150,000 miles on it, so that's probably a good suspect.
Thanks for the reply!