Paul wrote: but suspect the vibration is engine related, maybe a misfire. The injector harness has been replaced 3 months ago. Any ideas as to what may cause a misfire under these conditions??
Paul, I doubt it's a misfire - it would be very noticeable. My previous Defender started misfiring, and you couldn't miss it - it was similar to a vinyl skipping while playing.
The fact that your vibration occurs in a rev band points to a drivetrain issue. A simple way to diagnose this is to remove the front propshaft and then drive around (you have to lock the CDL). If the vibration disappears, then the problem lies somewhere in the front axle starting with the front diff. If it doesn't, then the problem lies somewhere with the back axle.
At least then you will have a starting point to work with.