Transfer case mount was missing on my 2011 l200 when I purchased it, so i replaced it , then a vibration throughout the cab began. I checked the alignment and everything is correct with no load on rubber bush retaining bolt, but as soon as i tighten it the cab vibrates. Loosen it off and the vibration goes away, but the mount is not secure then. Has any one experienced this before.

You may have a weak mount on the engine or gearbox that’s allowing more vibration than usual to be passed to the one you have fitted, if you get someone to sit in the truck and with the engine running take it to the bite point in first and reverse and see if the engine rocks excessively to one side, with a torch also look at the gearbox where it mounts for excessive movement. You can also use a bar between the gearbox and crossmember to lever on the box looking for movement it shouldn’t have