I have a 2004 Disco II with a Terra Firma lift, custom front shaft, rebuilt rear shaft and flex joint, but I have vibration at 45+ Mph under load as well as no load. If I maintain speed, with no large load I have no vibration. Took it to my driveline guy and seems to think the lift is causing the vibration. I have read somewhere that the engine mounts can be a cause of this type of vibration. Has anyone had experience with this type of issue?