I have owned several Discoveries, both 1 and 2 but on an 03 that i currently own, the motor vibrates a lot. it runs great, no issues with emmissions, it just shakes and the exhaust sounds more throaty than most.
Any ideas? Common balance or timing issues?

 

I should mention, the vibration is not tied to vehicle motion. It vaibrates at idle, and at every RPM.

 

Without looking at it physically its hard to judge but one thing I have seen is a broken flex plate that will make the engine vibrate alarmingly and emit strange noises.
TV

 

have you checked the motor mounts ??

 

I think the motor mounts look fine.
when you say flex plate, are you speaking of the rear drive shaft? If so, I would think that would only cause vibration while the vehicle is driving. My vaibration is equal at idle.