Very Bad Vibration

[dsmghost]

I would just tear it down to check all bearings and clearances and look for any damage. Also checking the torque of the shaft end nuts. Check the center and front diffs. Inspect the gears and everything else as you tear it down. It will likely be obvious. Make sure your clutch/flywheel assembly is ok and bolted/torqued flush to the crank but that's likely not your problem based on your description.