I had a very nice phone conversation with Richard Thorne as part of my research for a different final drive ratio. Craig Jezz told me that he has a buddy who has a 2014 4/4 (like me) but with a 3.9 rear axle from Richard Thorne. Richard confirmed this but he had no idea why this was the case and he hasn't seen it anywhere else.
Either you are that friend of Craig's or we have now established 2 4/4 with 3.9 gearing.

'14 4/4 graphite grey